Last night in Anaheim, Josh Hamilton had a really bad game. In five trips to the plate, he hit into three double plays, and in the two at-bats where he didn’t make two outs, he struck out, including a ninth inning whiff with the winning run in scoring position. For the day, he finished with a -.48 WPA, so while he didn’t single handedly cost them the game, he was the primary reason the Angels ended up dropping a 3-2 contest to the Mariners.

But I’m not here to lament Josh Hamilton again. His terrible performance is noteworthy, but I think it’s also worth acknowledging that Hamilton was fighting an uphill battle last night, because as a left-handed hitter in a game with John Hirschbeck behind the plate, he was screwed before he ever stepped up to the plate.

Via Brooks Baseball, here is a plot of the pitches Hirschbeck called strikes against left-handed hitters last night.

As you probably know, Major League umpires call strikes on a significant portion of pitches off the outside corner to LHBs, which is notated by the dashes that set off the “typical LH zone” on the left side of the rulebook strike zone. Last night, both Joe Blanton and Jeremy Bonderman pounded the outer section of the plate against left-handers, and were consistently rewarded with called strikes. In fact, Hirschbeck even expanded the normal lefty strike area further than usual, giving Blanton three strikes that didn’t fit into the already expanded strike zone. And, just for fun, he called a bunch of strikes on pitches that were below the knees as well.

By my count, there were 10 called strikes to LHBs last night that were not inside the boundaries of even the expanded LHB strike zone, and the plot of pitches to LHBs shows just how aggressive every pitcher was in taking advantage of Hirschbeck’s zone. The great majority of pitches to LHBs last night were low and/or away, and it gave the LHBs no choice but to swing at pitches they couldn’t really do anything with.

For instance, here’s the plot of pitches Hamilton swung at last night.

On a normal night, we’d look at the fact that eight of his 11 swings came on pitches out of the zone and just conclude that Josh Hamilton was still self destructing. But, really, what choice did he have last night? He swung at two pitches that were just outside — both well within the normal lefty strike area, much less within Hirschbeck’s zone — and five that were low but in spots that Hirschbeck was calling strikes for most of the evening.

Need proof of that? Here’s the pitches Hamilton did take last night.

Twice, Hamilton took a pitch that was low by rulebook standards only to have Hirschbeck call it a strike. He’s not the kind of hitter that needs to be incentivized to swing, but that’s exactly what Hirschbeck’s zone was doing last night. Swing or take a called strike; those were basically the two options that left-handers were faced with.

Hamilton wasn’t the only left-handed batter who had problems last night. Raul Ibanez and Kendrys Morales both struck out in three of their five trips to the plate, while Hamilton, Endy Chavez, and Kyle Seager all struck out twice. Joe Blanton tied a career high with 11 punchouts, putting up a 39.2% K% for the evening, more than double his overall strikeout rate for the season.

If it was just a one night thing, maybe Jeff would be writing a post about pitch framing, highlighting what Mike Zunino and Chris Iannetta did behind the plate to help their pitchers steal extra strikes. But with John Hirschbeck, this isn’t a one night thing. His reputation for having an exaggerated strike zone is well earned, and it’s most often expanded off the plate and down when a left-hander is at the plate.

From Baseball Heat Maps, here’s Hirschbeck’s called strike zone against LHBs during the PITCHF/x era.

And here’s Hirschbeck’s strike zone against right-handers, just so you can see how shifted the zone is when a left-hander is hitting.

And, just for reference, here’s some data. Multiple sports handicappers carry umpire data to assist those who wager on things like over/unders. For instance, here’s some umpire data from StatFox. Of the 69 home plate umpires they have tracked, Hirschbeck’s 2013 strikeout rate of 17.1 K/G is tied for fifth highest this season. 16 games isn’t a very big sample, so maybe you’d think that these numbers are biased because he’s happened to be behind the plate in a lot of NL ballparks, where strikeout rate is naturally higher. The game log, though, shows that 10 of his 16 games behind the plate have come in AL parks this year, and while there’s a Yu Darvish here and a Stephen Strasburg there, it’s not like he’s just had a steady stream of dominant hurlers on the mound.

Going further, I asked Jeff Zimmerman to send me the called ball/called strike/swing rates for every MLB umpire this year. I filtered out the umpires who have fewer than 500 called strikes on the sesaon, which left me with 70 umpires who have been behind the plate for a decent number of games this year. Out of those 70, Hirschbeck’s 19.1% called strike rate is tied for seventh highest.

Now, these numbers aren’t adjusted for the locations of the pitches that have been thrown, and in samples of just a few months, we shouldn’t draw any firm conclusions about an umpire’s zone based on called strike or called ball rates. In fact, a pitcher friendly umpire could have average called ball/called strike rates if the league knew of his reputation and hitters simply adjusted by swinging at more pitches off the plate, thus masking the fact that his zone is inflated. That’s why the location data is key here, and we have six years of data showing that John Hirschbeck’s strike zone is one of the more generous in baseball.

Last night was just the latest example of a long term trend. The Mariners put seven left-handed batters in the line-up against Joe Blanton, and he responded by simply pounding them down and away, letting the extra strikes pile up and turn into strikeouts. The Angels line-up is fairly right-handed, with Hamilton around to provide some left-handed punch, but he made eight outs in five trips to the plate in part because pitchers had even less reason to throw him a strike than usual.

The lefty strike has been around in MLB long enough that it’s almost certainly not going away, and everyone is aware of it enough that hitters and pitchers alike have adjusted to the reality of the shifted zone for LHBs. But, when an umpire takes the already enlarged strike zone and makes it even larger, he’s essentially neutralizing left-handed hitters. There is only so much room they can realistically cover while standing in the batters box, and if you force them to swing at every pitch thrown their way, you’re simply going to end up with low scoring, high strikeout affairs.

MLB has the data and the technology to crack down on stuff like this. If the league is really concerned about the rising strikeout rate, getting rid of unreasonably large strike zones is a good place to begin.