This isn’t really a quiz, just a wry chuckle about the limitations of Win Probability Added (WPA) for measuring a player’s game impact.
In Thursday’s 5-2 win, Miguel Cabrera went 4 for 5 with a HR and a double. His only out was a line drive; he was never picked off or caught stealing; and he made no errors.
So what was his WPA?
-0.018.
Yes, that’s a minus sign. The WPA method says that Cabrera’s total contributions reduced Detroit’s chance of winning by about 2%.
Almost all of Cabrera’s ABs were discounted, in a WPA sense, through no fault of his own:
— His double in the 1st came with 2 out and none on, so it barely moved the WPA needle — about a 2% positive impact on Detroit’s chance of winning.
— With 2 on, no outs and no score in the 3rd, his liner was turned into a brilliant leaping catch and DP, for a -13% impact. WPA doesn’t see Austin Jackson breaking too aggressively from 2nd base with no outs; it just sees the team’s probability of winning before and after the entire play.
— In the 4th, Cabrera singled with 2 on and 1 out, but Jackson ran into another out — this time at the plate, on a great throw and (probably phantom) tag — making the hit a negative event for Cabrera, -2%. WPA doesn’t care that Jackson pulled a Jeremy Giambi, standing when he should have slid, nor that on-deck man Prince Fielder was standing directly behind the umpire while gesturing for Jackson to get down, nor even that the ump called an out that he could not possibly have seen. (Watch every angle as often as you like, you’ll never know for sure if the tag was made — but in any case, it was physically impossible for the home plate ump to have seen the alleged tag on Jackson’s backside.) WPA’s motto is: “You hit it; you bought it.”
— In the 6th, Cabrera finally broke into the RBI column, singling home Jackson from 3rd (safe at last!) with 2 out. But they already led by 2 runs, so WPA rates it a modest 8%. (The way things were going, it’s a miracle the ball didn’t hit the pitching slab and land in Jeff Keppinger’s glove.)
— And lastly, his HR in the 9th restored a 3-run lead, but WPA saw that as just a 4% boost in win probability, or 1/3 as much absolute value as the line-drive DP.
This was the 282nd regulation games this century with 4 hits in 5 PAs, 1 HR and 1 double (all figures exact). Cabrera rated the worst WPA, and only one other was in the red. The other 280 games got higher WPA than Cabrera, even though:
- 91% of those hitters’ teams scored more than the 5 runs Detroit had; and
- 69% of the 230 wins were by larger margins than Detroit’s.
None of this is meant as a criticism of Win Probability Added. Every measurement has shortcomings; every record of an event contains some noise. We know that WPA simplifies things by ascribing all the credit or blame for every change of situation to just one offensive player and one defensive player. The negative assessment of Cabrera’s game was a fluke confluence of events, a perfect storm of sinister circumstances. It doesn’t mean WPA is a bad stat.
But if you want to introduce someone to the WPA concept, do yourself a favor: Keep them away from games like this for as long as you can.
