The Math on Letting Lance Lynn Hit
There were a bunch of turning points in Game 2 of the NLCS, including three late-game home runs that allowed the Cardinals to walk-off as winners. Yadier Molina‘s exit, due to a strained oblique, also looked like a big moment, especially when backup catcher Tony Cruz couldn’t handle Trevor Rosenthal’s game-tying wild pitch in the ninth inning. But, given the change in expected outcome, the biggest moment of the game might have actually occurred way back in the bottom of the fourth inning.
Already up 1-0, the Cardinals mounted a rally against Jake Peavy, with Matt Adams drawing a leadoff walk and Jhonny Peralta following with a single. Yadier Molina then laid down a bunt, which wouldn’t have made any sense if he was healthy, but it seems like he very well may not have been, which would help explain why he gave himself up to move the runners over. With first base open, the Royals easily decided to walk Kolten Wong, but then Randall Grichuk singled to drive in a run while also keeping the bases loaded.
At this point, the Cardinals had a 2-0 lead and three runners on with only one out. Their win probability had ballooned to 86%, in part because the run expectancy of a bases loaded/1 out situation is 1.5 runs, so while the Cardinals led only 2-0 at that point, the WPA graph was assuming that the inning would end with them either having a 3-0 or 4-0 lead, most likely. And that would make them overwhelming favorites to hang on and win.

