The Seattle Mariners are baseball’s hottest team at the All-Star break, and their rookie center-fielder Julio Rodriguez (“J-Rod” to his hometown fans) is a big reason why. More on Rodriguez and the Mariners after the jump.

Seattle’s current 14 game winning streak (tied with the Braves for this season’s longest) is one shy of the franchise record set in their 116 win season in 2001. That year, the Mariners debuted another rookie outfielder, Ichiro Suzuki, whose season included an All-Star selection, and RoY and MVP awards. This year, Rodriguez has the first and is well on his way to the second. The third will be a tall order for the 21 year-old from the Dominican Republic, but that’s hardly a slight on Rodriguez, who stands 6th in the AL with 3.6 WAR at the break, most of that garnered since May 1st, during which time he has posted an .886 OPS, including 16 home runs in 71 games. Those exploits have earned Rodriguez AL Rookie of the Month honors for both May and June, and a recent AL Player of the Week nod. That WAR total gives Rodriguez a shot at the debut season record for age 21 or younger players, a mark currently held by Ted Williams (1939) and Albert Pujols (2001), with 6.6 WAR totals.

How good has Rodriguez been to start this season? Looking at first halves (first half of schedule before 1933, before All-Star Game since) in debut seasons aged 21 or younger, Rodriguez ranks 5th in Runs Created, 3rd in Total Bases and Stolen Bases, 4th in Runs and Home Runs, 5th in RBI and Extra-Base Hits, and 6th in Hits. Another Seattle center-fielder, Ken Griffey Jr., is the only other player in the group with double-digit homers and steals before the break. Among all players this season, Rodriguez’s 18.2 Power/Speed number (i.e. the harmonic mean of home runs and stolen bases) leads the majors by a comfortable margin, and his 21 stolen bases are just one behind AL leader Jorge Mateo (if Rodriguez were to finish the season as the league stolen base leader, he would join Tim Raines, Mike Trout and Richie Ashburn as the only rookies to do so aged 21 or younger).

Rodriguez made his major league debut this season in Seattle’s opening day starting lineup. That accomplishment in an age 21 or younger season puts Rodriguez in pretty select company, as only 77 other position players* (and one pitcher) have matched that feat since 1901. Joining that group bodes well for Rodriguez, as the list is chock full of Hall of Famers and other notables, including such names as Tinker, Hartnett, Doerr, Williams, Ashburn, Mantle, Mathews, Aaron, Robinson, Pinson, Cepeda, Yastrzemski, Staub, Carew, Yount, Murray, Molitor, Griffey Jr., Pujols, Mauer and Tatis Jr.

* _{Of these 78 players, only two appeared in the same debut game. Larry Hisle and Don Money, both aged 20, debuted together for the Phillies on opening day 1968. Despite both recording their first hit that day (and Money driving in the game’s only runs in support of Chris Short‘s 4 hit shutout), the pair managed only 11 games and 26 PA between them for the season.}