It’s hard to overestimate the importance of Reed Johnson’s catch to rob Prince Fielder of a grand slam last night. If he didn’t catch that ball, the game would have been tied, the Cubs would have squandered a four-run lead, and odds are good that Dempster would have been pulled earlier in the game. The Brewers still got two runs in the inning, but they never got the game tied, and the Cubs escaped with a win.
But one way we can calculate it is WPA. Generally WPA focuses on batters and pitchers, but in this particular case, we need to only look at two possible outcomes to figure out what the play was worth. When Fielder came to the plate, the Brewers had a four-run deficit, the bases loaded, and no outs in the bottom of the fifth. They had a 28.7% chance of winning the game at that point.
After the play, even though a run scored, they gave up the out and the odds were good that they wouldn’t have a big inning. With men on first and third and one out in the bottom of the fifth, down by three, their odds of winning were 25.4%, per Fangraphs. Had that been a grand slam, though, it would have been a tie game, bottom of the fifth, no outs. That’s a 56.6% probability of winning for the home team.
In other words, Reed effectively robbed Fielder of .312 WPA on that one play. That’s almost three times more valuable than the most valuable offensive play of the game, Koyie Hill’s walk to drive in the go-ahead run in the fourth.
And a housekeeping note: no preview for the Rockies series. I plan on doing similar ones to the one I did for the Brewers series, but there are very few plate appearances for most of the hitters on either team against the others’ pitchers, so it wouldn’t be very interesting.