During last night’s Wild Card game live blog, there were a few readers (presumably Yankee fans) who were very upset with the strike zone being called by home plate umpire Eric Cooper.

10:42

Comment From Hank

Cooper is a joke – that one was 4-6? off the plate! Comment From Cb

Why is Sipp getting the benefit of the doubt on all these 3-ball count pitches on the edge? Comment From Will

I don’t think it’s been atrociously bad, but saying “it’s fair because both teams knew about it” ignores the fact that walk-heavy teams will be more burned by a pitcher-friendly zone than a free-swinging team like the Astros. Comment From The Hamburglar

Cooper’s zone is notoriously high. Once again, this does not explain the constant outside pitches going the Astros way

As we talked about pre-game, Eric Cooper is a known pitcher’s umpire with a tendency to call more strikes than average on pitches at the top and bottom of the zone. And that’s exactly what he did yesterday. From our box score page, a graphical representation of every called ball and called strike from last night’s game.

There are a couple of borderline calls on the right and left side of the plate, but by and large, the marginal called strikes are at the bottom of the zone, with a few extra at the top. If you go the box score page, you can actually hover over each point on the zone and see who threw the pitch, who was batting, and what the count was.

The call in that bottom left corner of the image, the one that was both low and inside to a right-handed hitter? That was thrown by Masahiro Tanaka, a first pitch called strike to Evan Gattis. That one went the Yankees way, and it was pretty clearly the worst call of the night. So, sorry Hank, there was no pitch “4-6 inches outside” that went against the Yankees.

That said, Dallas Keuchel did benefit more from the calls on the margins than Tanaka (or any of the Yankees relievers) did. The lowest pitch that was over the plate and called a strike was a 2-1 fastball to Brian McCann that evened the count. The one just above that was a 1-0 cutter to Chase Headley. On the other side of the plate, the one just below the zone that was called a strike was a 1-0 fastball to Rob Refsnyder. The called strike the furthest to the right on the graph was a 1-0 fastball from Tony Sipp to Refsnyder. The called strike the furthest to the left (besides the Tanaka/Gattis pitch) was a 2-0 fastball from Keuchel to Chris Young.

All of these borderline pitches could have been called balls, but I included the count in those descriptions for a reason; notice how, in every single one of those, the batter was ahead in the count. This shouldn’t be a surprise, because it’s pretty well established that the strike zone gets bigger when a pitcher falls behind in a count, and shrinks as a pitcher gets ahead.

Despite the cliche about “needing to give in to a hitter” when a pitcher falls behind, the reality is that a pitcher with good command can actually push the edges of the zone a little more aggressively after he throws ball one or ball two, because umpires are more generous with their calls in those counts than they are if a pitcher is trying to paint the corner for strike three. While I’m certainly not a psychologist, it seems to make intuitive sense that umpires, as human beings, are incentivized to minimize the number of at-bats where they determine the outcome on the final pitch, so shrinking the zone with as a strikeout becomes possible and growing it as a walk becomes possible seems to fit with the motivation of having the at-bat end with a player action rather than an umpire call.

So, yes, Keuchel got some calls on pitches on the borders of the strike zone, but in almost every single case, he threw those borderline pitches in counts where the zone is known to expand in size. And a majority of these borderline pitches that were called strikes were just below the bottom of the strike zone, which is an area where Cooper is known to be more generous than the average umpire. Given the “presentation” skills of his catcher, Cooper’s tall strike zone, and the counts in which he was pounding the bottom of the strike zone, we shouldn’t be at all surprised that Keuchel got the benefit of the doubt on pitches at the margins. Tanaka would almost certainly have gotten those calls too, except he didn’t command his pitches well enough to paint the corners very often.

There’s no question that Cooper’s zone was a little bit larger than most umpire’s zones, but that’s true of him in general, and was known heading into the game. With basically one exception — a pitch that gave Tanaka a free strike on a pitch that wasn’t very close — Cooper called the strike zone that both teams should have expected him to call. Keuchel did a better job of taking advantage of Cooper’s willingness to call low strikes, especially by attacking those borderline areas even after he fell behind by a ball or two, but this wasn’t a situation where the umpire was egregiously calling pitches one way and not the other.

The Yankees offense struggled last night, and having a pitcher-friendly umpire certainly didn’t help promote offense, but Cooper’s tall strike zone was a known variable heading into the game, and that’s what he called last night. The Astros simply did a better job of executing pitches in areas that Cooper would call strikes.