Last night, the Yankees and Indians combined to strike out 31 times, the most strikeouts ever recorded in a playoff game that didn’t go extra innings. And during our live blog, complaining about the size of Jeff Nelson’s strike zone was a common occurrence. Accusing the home plate umpire of malfeasance is a regular thing fans do, especially in the postseason when the stakes are the highest, but in looking at the data today, there is some validity to the arguments. Last night, Jeff Nelson called a pretty huge strike zone.

For instance, let’s look at this second inning at-bat from Austin Jackson. He struck out on four pitches. He didn’t swing the bat once.

The first two pitches of the at-bat were at the top of the zone, one called a ball, one called a strike. The last two were both near the outside corner, the 1-1 pitch being closer to the plate than the 1-2 pitch. All of these pitches are in that gray area where some umpires call them strikes, some call them balls, and no one calls them all the same thing every time.

Last night, Nelson just called more of those pitches strikes than hitters are used to.

Baseball Savant has a detailed strike zone grid where they break up the zone to include all the borderline areas. That lets us search for just pitches in those edges. For instance, here’s every pitch in one of those borderline zones that has been called a strike during the postseason.

There’s 487 called strikes in those zones, representing 23% of the 2,138 pitches that have been classified as landing in one of those boxes. That’s up slightly from the 22% strike rate for these pitches in the regular season, which, as Jeff noted yesterday, is evidence that the strike zone gets a little bigger in October.

Last night, there were 126 pitches thrown in those zones; Jeff Nelson called 39 of them strikes. That’s 31% of those borderline pitches going the pitcher’s way. Nelson has one of the biggest strike zones during the regular season, but last night, he was particularly generous, which is one of the reasons why CC Sabathia was able to strike out nine of the 18 batters he faced.

But despite highlighting Jackson’s at-bat, Cleveland fans can’t really blame Nelson for last night’s loss. Their pitchers benefited just as much as the Yankees did.

21 of the 39 borderline called strikes were thrown by Cleveland pitchers. Kluber, Allen, Miller, Shaw, and Smith had 33% of their borderline pitches called strikes, while Sabathia, Robertson, and Chapman had 30% of their borderline pitches go in their favor.

Now, you could argue a bigger zone in general perhaps helps Sabathia more than it does Kluber, since Sabathia relies more on location and less on stuff, and a larger zone neutralizes some of the advantage Cleveland thought they had in starting pitching heading into the night. Of course, the flip side is that a smaller zone probably would have led to Sabathia leaving the game earlier, which would have likely meant Chad Green pitching some of the innings Sabathia threw, and Green doesn’t need a large strike zone to dominate opposing hitters.

So I wouldn’t say that Nelson’s large strike zone strongly benefited one team more than the other. It definitely was a factor in why the two teams combined for 31 strikeouts, though. And if Jeff Nelson gets an ALCS assignment, the hitters should probably go up there swinging.