The Most and Least Generous Strike Zones

On a few occasions over the winter, I theorized that we might be seeing the beginning of the end of pitch-framing value. It has nothing to do with the idea of an automated strike zone. Rather, I think there are two factors. One, umpires have an increasing awareness of framing reputation, and that can have effects, even if they’re not intended. And two, as teams develop and acquire better framers, that raises the floor, and in turn it raises the average, making it more difficult to stand out. You know — if everyone has a good framer, no one has a good framer. That sort of thing. I do genuinely think that we’re in a transition period.

But things are still transitioning. This is something that would play out over several seasons, not one or two. Framing is very much still alive, meaning the idea of differing strike zones is very much still alive. Fair? Unfair? Don’t know! But we’ve got numbers. Here come some early-season numbers.

This is something I write about a few times every year. So the posts are never original, but the information is always up to date. If you remember these posts from before, you can skip ahead. If you don’t, here’s the deal. For every team, it’s easy to see how many pitches they’ve thrown, and how many strikes they’ve generated. Yet using plate-discipline information available on FanGraphs, it’s also easy to calculate a total number of expected strikes. So you’re left with actual strikes and expected strikes. Differences are informative. A team with more strikes than expected strikes has worked with a favorable zone. A team with fewer strikes than expected strikes has worked with an unfavorable zone. You follow, because you are smart.

A big chunk of this is about catcher framing. But you also have run-of-the-mill luck, and plus there’s pitcher identity to take into account. Some pitchers just earn better zones than others, typically because they possess better command. Now, these numbers aren’t perfect, because the PITCHf/x system isn’t perfect. So this isn’t gospel, but below are my results. To this point, the Astros have pitched to the most generous zone. The White Sox have pitched to the least generous zone. That already tells you this isn’t the most important thing in the world, but it’s definitely a thing in the world.


To put numbers to it: By this measure, the Astros are at +43 strikes. The White Sox are at -40 strikes. The Astros have a generally frame-able pitching staff, and they get reliably good work behind the plate from Jason Castro and Erik Kratz. The White Sox opted to exchange catcher defense for catcher offense. The funny thing about that is the offense has still been bad, but at least the defense has also been bad, with a lot of this the result of poor framing from Alex Avila and Dioner Navarro. The Sox don’t have too much to complain about, but they’d at least like to see some hits.

While the Astros and White Sox stand at opposite extremes, they’re not the only teams well distant from zero. It shouldn’t be a surprise to see the Pirates near the lead. Francisco Cervelli is an excellent receiver, and the Pirates have a plan for everything. The Orioles are somewhat surprising, a credit to Caleb Joseph. The Brewers’ position indicates good things about Jonathan Lucroy, and then you have the Rockies, who’ve benefited from the work of whoever Tony Wolters is. Turning things around, it feels like the Tigers are always near the bottom of these lists. This is also just another place the Braves struggle, and then with the Marlins, Jeff Mathis doesn’t play enough to defensively cancel out J.T. Realmuto. The A’s, I think, blend mediocre receivers with a tough-to-catch staff. The upcoming debut of Henderson Alvarez might not help that. Not that his return isn’t something to look forward to.

It’s early, on the team level, which means it feels even earlier on the individual level. And as individual pitchers go, I don’t want to spend too much time discussing them yet, but I’ll say Chase Anderson is presently the leader in extra strikes, at +16. He’s followed by Francisco Liriano and Alex Wood, at +15. Mike Pelfrey stands at a rather sad -19. Then Eric Surkamp and Rich Hill are teammate-tied at -17. Carlos Rodon has been the most difficult White Sox pitcher to receive, which shouldn’t be a shock!

Quickly, let’s go back to team-level stuff. Is it still too early, or is there signal here? I looked at the data from 2015, comparing extra strikes in April to extra strikes in May through September. I put everything over a common denominator, and this was the result:


I examined just one year, which is probably insufficient, but you can still see a relationship. Teams with good or bad April numbers tended to be teams with good or bad May-September numbers. In the event of a big change, that was usually linked to a change in personnel. Like, the Marlins started poorly, but they quickly ditched Jarrod Saltalamacchia, and they eventually played more Mathis. The Rays wound up playing less Rene Rivera, and the A’s got a spurt of lousy framing from Carson Blair. With the Padres, Derek Norris just got better at framing over the course of the season. The Astros were good early and good later. Same with the Pirates. Same with the Cubs. The Tigers were the opposite. So were the Braves, and so on and so on.

It’s not too early to read into all this. It is too early to think it’s massively important, and actually, it’s just never massively important, relative to other things. That much, we all understand. But the year is 2016, and baseball teams continue to pitch to different strike zones. This is how it’s always been, so I suppose you could consider this a link to baseball history.

Jeff made Lookout Landing a thing, but he does not still write there about the Mariners. He does write here, sometimes about the Mariners, but usually not.

Newest Most Voted
Inline Feedbacks
View all comments
7 years ago

The White Sox have a 2.24 team ERA despite losing 40 strikes. Remarkable.

7 years ago
Reply to  trenkes

And the pirates have the second worst pitching WAR in the majors despite getting an extra 35 strikes!