Last September, Baseball Reference added the Championship Win Probability Added (cWPA) statistic to their website. The stat, developed by Dan Hirsch, assesses the impact of each play in improving a team’s chances of winning a championship. It’s an intuitive concept: a go-ahead home run in a World Series is more impactful than one in mid-August. Consequently almost all of the biggest single plays by cWPA have come in October.

But what of the humble regular season? Less consequential than the playoffs, for sure, but still full of dramatic moments that can pave the way for postseason success. Here, then, are the plays that have had the biggest positive effect on each team’s chances of winning the World Series, going in order from the least to the most pivotal.

The 2010 and 2011 Rangers had won their division at a canter and reached the World Series both times. The 2012 Rangers entered their final series of the season having led the AL West since April 9th. But two losses to the A’s brought Oakland into a first-place tie, setting the stage for a final day division shoot-out.

A third inning Texas rally gave the Rangers a 5-1 lead, with Murphy’s two-RBI knock the biggest hit. But a brutal Josh Hamilton error capped a fourth inning capitulation, and Oakland snatched the division title. Texas were forced into the inaugural AL Wild Card Game, which they lost.

#28: Miami Marlins: Jeff Conine hits an seventh inning, game-tying home run against the Wild Card rival Phillies; September 23, 2003. cWPA: 1.52%

The Marlins are the only team to parlay a Wild Card berth into a World Series title on multiple occasions, a feat made easier by the lack of a Wild Card Game in 1997 and 2003. Well out of the division race in the latter season, the Marlins faced a crucial, late-September series with the Phillies: their closest rivals for the Wild Card spot.

In the first of these games Philadelphia held a three-run lead, before walks to Derrek Lee and Miguel Cabrera in the seventh set the table for Mr. Marlin. Conine’s home run tied things up, the Marlins won the game, and the ensuing series sweep all but wrapped up the NL Wild Card race.

#27: New York Mets. Duffy Dyer’s two out, ninth inning double ties it up vs the division leaders; September 20, 1973. cWPA: 1.92%

As dawn rose on September 18, 1973 the Mets were in fourth place in the NL East. By midnight of September 21, they were in first. Along the way they had beaten the erstwhile division leading Pittsburgh Pirates four times.

The third of these games featured Duffy Dyer’s last gasp RBI knock to level the score, the miraculous “Ball on the Wall” play, and a 13th inning Ron Hodges walk-off which drew New York to within half a game of Pittsburgh. Victory in the following day’s game gave the Mets their first outright division lead of the season. They were not to be caught.

#26: Los Angeles Angels: Darin Erstad’s two run double ties the game in a division deciding clash; October 2, 2004. cWPA: 2.16%

The Angels and A’s faced off in the final three games of the season with the AL West at stake. Anaheim had been trailing Oakland for the back half of the 2004 season but had drawn level coming into this series. Without a Wild Card to fall back on, it was winner takes all.

The Angels won the first game, meaning they could seal a postseason spot with a victory in the second encounter. Oakland’s 4-2 lead disappeared in the eighth on Darin Erstad’s first pitch, two-RBI double. Erstad himself scored the go-ahead run later in the inning and the Angels clinched the division.

#25: Seattle Mariners: Luis Sojo clears the bases in the AL West tie-breaker game; October 2, 1995. cWPA: 2.33%

While many of the games already mentioned functioned as effective division deciders, this is the first official tie-breaker game on the list. The Mariners, who had been 12.5 games back on August 20, capitalized on the Angels collapse to tie Anaheim atop the AL West and force a play-in game.

Seattle took a slim one-run lead into the seventh, but blew the game open on Luis Sojo’s bases loaded, broken bat double down the right field line, with Sojo himself scoring on the play after a wild throw home by the first baseman. The play’s tenure as the most famous hit in Mariners history lasted less than a week.

#24: Kansas City Royals: Frank White homers for a 2-0 lead over the Angels; October 3, 1985. cWPA: 2.49%

Another decade, another top-of-the-division bout involving the Angels. White’s first inning dinger off Don Sutton gave the Royals all the runs they’d need and sent them to the top of the AL West, one game ahead of the team from California. Both teams went 2-1 in the final three games, enough for the Royals to take the divisional crown en route to a World Series title.

#23: Milwaukee Brewers: Don Sutton retires Eddie Murray with the bases loaded on the final day of the season. October 3, 1982. cWPA: 2.65%

This is the only entry on this list by a pitcher. While a hitter can knock in up to four runs on one pitch, there is no corresponding single positive action for a pitcher, making it much harder for them to produce a high cWPA on one play. Shutting down a bases loaded situation in a tight game is about the only way to do it.

And so, three years before Don Sutton was giving up the biggest hit in Royals regular season history, he was throwing the biggest pitch in Brewers regular season history. Milwaukee entered the final series of the season with a seemingly comfortable three game lead over the Orioles. But the O’s defeated Milwaukee in three consecutive games in Baltimore to make Game 162 a shoot-out for the AL West title.

The Brewers built up a 3-1 lead heading into the bottom of the fifth, but Baltimore loaded the bases for Eddie Murray, whose .940 OPS that season trailed only Milwaukee’s own Robin Yount in the AL. Murray rifled a grounder past the first base bag, but Cecil Cooper made a nifty grab and ran to the bag unassisted to end the inning. Several minutes and one pitch later, Cooper smoked a homer off Jim Palmer to extend the Brewers lead and suck any remaining life out of the home crowd. Milwaukee got the one win they needed and advanced to the ALCS.

#22: Tampa Bay Rays: Dan Johnson hits a two-out, two-strike, game tying home run in the bottom of the ninth in Game 162; September 28, 2011. cWPA: 2.83%

You know this one. In the ninth inning of the final day of the season, Dan Johnson, undisputedly the most famous sub-Mendoza Line hitter in Rays history (until this past October at least), hit a line drive, game-tying home run. Evan Longoria, a more conventional hero, hit a game winning dinger a few innings later. Paired with Boston’s month-long collapse (and ninth inning collapse on this particular date), the Rays clinched an improbable Wild Card spot.

Why isn’t this higher on the list? For one, Johnson’s homer only tied the game. For two, there were still three playoff rounds between the Rays and a potential World Series title. And for three, even if the Rays had lost this game, they still would have had the luxury of a one-game tiebreaker for the Wild Card if the Red Sox also lost (which they did).

Still, this homer is about as big as it can get in the Wild Card era. There have been only two regular season games since 1995 that featured a bigger play than this.

#21: Cincinnati Reds: Leo Cardenas’ game-tying, RBI triple ignites an eighth inning comeback vs the division rival Dodgers; August 27, 1961. cWPA: 3.35%

That a game in August appears on this list is surprising, but once again demonstrates the increased value of the regular season in the days when the World Series was the postseason.

It also highlights the importance of head-to-head encounters. Without Cardenas’ triple, the Reds probably lose and go into the second game of that day’s double-header only half a game ahead of the Dodgers. With the triple, the only one Cincinnati’s 22-year-old shortstop tallied all year, the Reds were in a position to win the game and go 2.5 games up in the division. Cardenas scored two batters later to seal the win, and a victory in the second game gave the Reds a comfortable division lead that they never relinquished.

#20: Chicago White Sox: Eddie Collins’ walk-off keeps the Sox in the race; September 19, 1916. cWPA: 3.42%

The American League pennant race in 1916 saw a three way battle between the Red Sox, Tigers and White Sox, who were all within two games of each other on September 20. To keep themselves in the hunt, Chicago needed a win over the Philadelphia Athletics in that day’s game. That shouldn’t have been too difficult: the 1916 A’s finished with a winning percentage of .235, which remains the lowest in MLB history since 1901.

But a late A’s rally left the White Sox facing a two-run deficit in the bottom of the ninth. A sac fly reduced the arrears to one and a Buck Weaver walk loaded the bases for Eddie Collins. Captain Collins came through in the clutch by doubling home the tying and winning runs; pitcher Tom Sheehan’s record worsened to 1-16 on the season.

The White Sox stayed just a game and a half back of Boston, but that was as close as they ever got to the eventual AL champs.

#19: Washington Nationals / Montreal Expos: Ellis Valentine hits a go-ahead single in the ninth to keep Montreal ahead of the Pirates in NL East; September 24, 1979. cWPA: 3.46%

The disco-inspired 1979 Pirates were only able to win that year’s World Series after withstanding a tough divisional battle with Montreal. If a late September series had gone differently, perhaps we’d be reminiscing about the “Nous Sommes Une Famille” Expos.

As it happened, the Expos fell just short in their attempt to reach the postseason for the first time in franchise history. Montreal entered their penultimate series of the season – a four game set in Pittsburgh – half a game up on the Pirates. The first encounter went Pittsburgh’s way, but Ellis Valentine’s ninth inning, two out, tie-breaking single in the second game helped reclaim their slim division lead.

It wasn’t enough: Les Expos dropped the next two to the Pirates, lost their final series, and Pittsburgh went on to claim a famous title.

#18: Houston Astros: Art Howe homers for an insurmountable lead in the NL West tiebreaker; October 6, 1980. cWPA: 3.60%

All the Astros had to do to win the West was to not get swept by the second place Dodgers in the final series of the season. In Game One they were one out away, but Ron Cey’s grounder found a hole to tie it, and Joe Ferguson walked it off in the 10th. In Game 2 the Astros wasted a rare no-walk start from Nolan Ryan and lost 2-1. In Game 3 Houston blew a 3-0 lead, capped by Ron Cey’s two-run lead changing home run in the eighth inning.

Having wasted three chances to secure the division and the first postseason berth in franchise history, the Astros took no time in taking the lead in the tie-breaker. Small ball and Dodgers errors gave Houston a 2-0 advantage in the first inning and Art Howe (aided by a close two strike call earlier in the at bat) put the game to bed with a two-out, two run homer in the third. Houston went on to win 7-1, claiming the spoils in the first one-game playoff in NL history.

#17: Oakland / Philadelphia Athletics: Max Bishop’s solo shot in the ninth vs the Yankees keeps the AL race close; September 12, 1928. cWPA: 4.06%

The A’s had recently woken up from their fire sale induced, decade long slumber, and were serious challengers to the Yankees for the AL crown in 1928. The ballclub featured a remarkable array of talent, from young stars Jimmie Foxx, Al Simmons, Mickey Cochrane and Lefty Grove, to veterans Ty Cobb, Tris Speaker and Eddie Collins.

It was Max Bishop who led the team in position player WAR, though, and the second baseman’s two out tie-breaking home run in the ninth inning vs the Yankees on September 12 prevented the A’s from suffering a four game sweep. The win kept them within a game and a half of New York. The three previous losses had done too much damage though, and the A’s couldn’t overhaul the reigning champs in the final two weeks of the season.

#16: San Diego Padres: Scott Hairston’s homer gives the Padres a two-run lead in the 13th inning of the NL Wild Card tie-breaker game; October 1, 2007; cWPA: 4.19%

San Diego posted a 15-13 record in September, which was respectable enough but not sufficient to overhaul the Diamondbacks for the division lead. Worse was the Padres losing five of their last six matchups with the Colorado Rockies, enabling the latter to force a Game 163 to determine the NL Wild Card.

In the tiebreaker, Triple Crown winner Jake Peavy was rocked for six by the Rockies offense, negating a five-run outburst by the Padres in the third. But a clutch Brian Giles double in the eighth (aided by some suspect Matt Holiday defense) tied things up at six apiece, and the score remained unchanged until the 13th inning. Giles led off the top of the inning with a walk, and Scott Hairston followed by homering over the head of an onlooking Holliday.

Did the Padres hold on to this lead? We’ll find out later.

#15: Atlanta / Milwaukee Braves: Johnny Logan’s homer saves the game in the ninth; September 22, 1956. cWPA: 4.70%

The Braves led the NL for most of 1956, but could never quite shake the Dodgers, or the Reds for that matter. A victory on September 22 versus the last placed Cubs would eke out a one game league lead. Johnny Logan’s game-tying solo shot to lead off the bottom of the ninth staved off a loss in regulation, but the Cubs conjured a run of their own in the tenth and the Braves remained tied with Brooklyn in the standings. A 3-2 finish to the season was not good enough (Brooklyn went 5-2 from this point on), and the Braves long wait for a second championship would go on.

#14: Detroit Tigers: Rudy York plates two in the eighth as Detroit kicks off a key series with a comeback win. September 20, 1940. cWPA: 5.24%

At the start of play on September 20, 1940, Detroit and Cleveland were tied atop the AL. Both teams were capitalizing on a down-year from the Yankees, who were playing an entire season without one of Babe Ruth or Lou Gehrig for the first time since the deadball era. Each team had eight to play, and six would be against each other (three at home, three away).

In the first game in Detroit, the Tigers were down 4-1 before chasing Mel Harder in the eighth. Cleveland’s Bob Feller came in from the bullpen but was unable to put out the fire. Detroit tallied three consecutive singles to grab the lead, with York’s hit (the middle of the bunch) plating two to tie it.

Detroit won the encounter, and would win the AL by just one game.

#13: Toronto Blue Jays: Junior Félix’s two run homer flips the lead in the ninth vs the Red Sox in a top of the division clash; September 28, 1990. cWPA: 5.26%

The Blue Jays and Red Sox were tied atop the AL East with six games to play, the first three of which saw the division toppers square off in a huge series in Boston. In the first game, Toronto clawed back from a 4-0 deficit in the the seventh, but gifted Boston a one-run lead in the eighth on consecutive Kelly Gruber throwing errors.

Greg Myers singled to lead off Toronto’s half of the ninth, and Junior Félix silenced the Fenway Park crowd by jumping on the first pitch to give the Blue Jays their first lead of the night.

If Toronto had held onto the lead perhaps this would be known as the “Junior Félix Game”. Unfortunately for Torontonians, it would end up being remembered (in Boston at least) as the “Jeff Stone Game“. The Sox rallied in the ninth, and after Mike Greenwell tied things with a single, Stone, who had entered in the eighth as a pinch runner, knocked in the winning run. It was Stone’s only hit of the year and the final hit of his major league career. Boston took a one game lead in the division, split the next two games with Toronto, and the Jays were unable to recover.

#12: Minnesota Twins / Washington Senators: Wade Lefler clears the bases and gives Washington the lead in a key late season game. September 27, 1924. cWPA: 5.49%

The Senators entered their final series of 1924 with a two game advantage over the Yankees and their destiny in their own hands. But a loss to Boston in the first game of the series tightened their league lead to just one game.

In the second game they trailed by two through four innings. With two outs and the sacks full of Senators in the fifth, Wade Lefler cleared the bases to give Washington the lead. The Sens won the game, and captured their first AL pennant twenty-four hours later.

#11: Colorado Rockies: Matt Holliday hits an RBI triple with nobody out to tie it up in the 13th inning of the NL Wild Card Tie Breaker; October 1, 2007; cWPA: 5.90%

No, the Padres did not hold onto their lead (see #16). San Diego’s two-run edge in the 13th could not withstand back-to-back doubles followed by Holliday’s game-tying triple. With nobody out, Holliday was almost guaranteed to score from third, although he was abetted by a highly suspect home plate call on a sacrifice fly. Rocktober was under way.

#10: Baltimore Orioles / St. Louis Browns: Chet Laabs’ two-run home run gives the Browns the lead on the final day of the season; October 1, 1944. cWPA: 6.59%

The Browns improbable pennant win in 1944 came down to the final day. The Tigers had gone 40-15 in August and September to force a tie at the top of the AL. To guarantee their first ever trip to the World Series the Browns would have to beat the Yankees, just as they had in the previous three games, and hope Detroit lost to Washington. An all-St. Louis World Series was in the cards.

The Yankees jumped out to a 2-0 lead, but Chet Laabs two-run dinger squared it up in the fourth. This was not his biggest two-run smash of the game, however. One inning later, Laabs again victimized rookie pitcher Mel Queen to give the Browns a two-run lead they would not relinquish. Detriot lost, and the Browns advanced to the first and only Streetcar Series.

#9: St. Louis Cardinals: Andy High doubles in two to give the Cards the lead in the ninth vs the rival Dodgers. September 17, 1930. cWPA: 6.64%

The 1930 pennant race saw the Cardinals, Dodgers and Cubs vying for National League bragging rights. Andy High’s pinch hit, ninth inning RBI double on September 17 not only broke a tie with Brooklyn in the game, but also one at the top of the standings as the Cardinals forged ahead of the Dodgers.

The victory also kept St. Louis a game and a half ahead of Chicago, and they needed every win as the Cubs stormed to a 7-2 finish. Brooklyn fell out of the race, but the Cardinals finished 8-2 to seal the pennant.

#8: Pittsburgh Pirates: Bob Robertson’s two run dinger flips the lead in the eighth; October 1, 1974. cWPA: 7.16%

Everything changed in the eighth inning on October 1. With two games to go in the season the Pirates and Cardinals were tied at the top of the NL East. But the Pirates were losing 5-4 at home to the Cubs, while the Cardinals were 2-1 up in Montreal; the Redbirds were set to take a one game lead into the final game.

But two swings changed all of that. Montreal’s Mike Jorgenson hit a two run homer off ageing St. Louis ace Bob Gibson to put the Expos on top. And in Pittsburgh, Bob Robertson’s pinch hit two-RBI homer gave the Pirates the lead.

It was the Pirates, then, who entered the final day with a one game lead, and a dramatic 10th inning walk off victory on October 2 (aided by Robertson’s clutch run-scoring strikeout in the ninth) sealed the division title.

#7: Philadelphia Phillies: Dick Sisler’s extra innings three-run homer wraps up the pennant; October 1, 1950. cWPA: 9.50%

The Phillies were looking for their first pennant since 1915, but had been stumbling toward the finish line. A 7.5 game lead over Brooklyn on September 20 had been cut to two by the end of September 29. If the Dodgers could beat the Phillies twice in the final two games of the season, a three-game playoff would be required to decide the pennant.

Brooklyn won the first game 7-3. The second game was a classic. Don Newcombe took the mound for the hometown Dodgers while Robin Roberts got the start for the Phillies, and the two young aces allowed just one run each through nine. Roberts and Eddie Waitkus singled to start the Phillies tenth, and after a failed sac bunt by Richie Ashburn, Dick Sisler smoked a three run homer to left field to put the Phillies on top. Roberts put down the Dodgers 1-2-3 in the bottom of the tenth, and Philadelphia advanced to the World Series.

#6: Chicago Cubs: Gabby Hartnett’s Homer in the Gloamin’ claims the division lead for Chicago; September 28, 1938. cWPA: 9.71%

The Cubs had been chipping away at the Pirates’ league lead since August 20, a date that saw Chicago a whopping nine games back in the standings. Even as the calendar turned to September the Cubs were still seven games back. By the time the Pirates arrived in Chicago for the penultimate series of the season, Pittsburgh’s lead was down to a game and a half. A sweep would see Chicago overtake their rivals.

That’s exactly what happened. A tight 2-1 victory in Game One was followed by a comeback win in Game Two. Two runs in the Chicago half of the eighth leveled the score before Gabby Hartnett’s home run in the fading light sealed the win. Chicago had their first league lead since June, and when they completed the sweep of the Pirates the next day their lead was a game and a half with four to play. Pittsburgh could only muster a 1-3 finish, and the pennant went to Chicago.

#5: Cleveland: Ken Keltner’s three run blast gives Cleveland the lead over Boston in the first AL tie-breaker; October 4, 1948. cWPA: 9.84%

On September 24, 1948, the AL teams from Cleveland, Boston and New York shared the league’s top perch with only seven games to play. Cleveland nudged ahead prior to the final game of the season, but a loss to Detroit, paired with Boston’s victory over the Yankees, meant a one-game playoff would be necessary to separate Lou Boudreau’s team and the men from Fenway Park.

The first play-in game in AL history started with the two teams trading blows in the top of the first. With the score tied at one each in the fourth, Ken Keltner smashed a three run home run over the Green Monster to give Cleveland a 4-1 lead over Boston. The visitors ran out 8-3 winners and advanced to the World Series, winning what remains their most recent championship in franchise history.

#4: Boston Red Sox: Carl Yastrzemski keeps the Impossible Dream alive with a game-tying, bases loaded single on the final day; October 1, 1967. cWPA: 10.49%

On the morning of the final day of the 1967 season only half a game separated the top three teams in the American League. The Red Sox and Twins were squaring off at Fenway. Either team could book their place in the World Series with a win, as long as the Tigers didn’t sweep their double header with the Angels. If Detroit won both their games, a tie-breaker would be required.

The Red Sox trailed by two through five and a half, but cracked Minnesota’s pitching in the sixth. The Sox hit three consecutive singles to load the bases, teeing up Triple Crown winner Carl Yastrzemski’s game-tying single. The wheels then really came off for the Twins: a fielders choice, two wild pitches, a walk and an E3 scored three more runs for Boston. The Red Sox held on to win, and after Detroit lost the second game of their double-header Boston was headed to the World Series.

#3: New York Yankees: Bucky Dent earns a profane nickname with a three-run, go-ahead home run in the AL East tiebreaker; October 2, 1978. cWPA: 11.60%

The third final day, Fenway Park game in a row on this list, and the most famous of the bunch. The story is well-worn: light hitting shortstop Bucky Dent turns a 2-0 deficit into a 3-2 lead for the Yankees on one swing against their most bitter rivals. The lightning in Dent’s bat continued into the World Series as he knocked in three RBIs in the decisive Game 6 and earned MVP honors.

#2: Los Angeles / Brooklyn Dodgers: Tommy Davis flips the lead with a two-run homer in the decisive third game of the NL tiebreaker series; October 3, 1962. cWPA: 15.39%

It really doesn’t get much better than this: a back-and-forth, pennant-deciding game between two fierce rivals, hot on the heels of a similarly topsy-tuvy game the day prior. Tommy Davis was no Bucky Dent – his triple crown stats in 1962 (.346 BA, 27 HR, 153 RBI) speak for themselves – but his lead-flipping home run in the sixth inning of this game could have been the Dodgers’ Dentian moment.

It wasn’t to be. An inch-by-inch ninth inning Giants comeback turned a 4-2 Dodgers lead into a 6-4 advantage for San Francisco, and L.A. went down quietly in the bottom of the ninth. The ninth inning turnaround surely brought back painful memories for any transplanted Brooklyn Dodgers fans…

#1: San Francisco / New York Giants: Bobby Thomson hits the Shot Heard ‘Round the World; October 3, 1951. cWPA: 35.56%

To finish off the quote in this article’s headline ” … it’s gonna be, I believe… The Giants win the pennant! The Giants win the pennant! The Giants win the pennant! The Giants win the pennant!”

You knew this was coming. Nothing in the history of the regular season has come close to the impact of this play. Thomson’s two-on, one-out walk-off home run has a (rounded) cWPA of 36%, the same figure as the bottom 14 plays on this list combined. Its cWPA is more than double that of Davis’ home run at #2 on the list.

And with the continuing additions to the postseason, we can safely say that no regular season play will ever approach the importance of Thomson’s shot.