Baseball defense is hard to measure. Catcher defense is even harder. There are a lot of different aspects of catcher defense, including:
- Controlling the running game
- Actually fielding the ball
- Preventing passed balls and wild pitches
- Pitch framing and umpire psychology
- Game-calling and pitcher psychology
For the longest time, #1 was all we looked in stats like WAR. #2 a comparatively small part of the game while also being difficult to measure. #5 is anyone's guess. Some work has been on #3, but I'm not sold on it yet. That leaves us with #4: getting umpires to call balls as strikes, and strikes as strikes.
Measuring pitch framing is actually pretty easy. We have Pitch/Fx data about where a ball ended up. We have a good idea of where the strike zone should be. Therefore, we can count up pretty large sample sizes of called strikes that should be balls, and called balls that should be strikes. Do the math, and you know how many more strikes a catcher was able to call versus the average.
How good is Brian McCann? One of the best in baseball. From 2008-2013, McCann saved 22.2 runs per 7000 opportunities with pitch framing alone, according to an article by Pavlidis and Brooks at Baseball Prospectus. Among current MLB starting catchers, McCann is second only to Jonathan Lucroy.
Using fWar, which accounts for catcher defense around base runners but nothing else, McCann was worth 3.8 wins per season over that time frame. That's pretty good. But add pitch framing to the mix, and McCann turns into a 6+ win player over that time span. McCann was roughly equivalent to Robinson Cano from 2008-2013, even after accruing less playing time.
I don't know about you all, but this blows my mind. I knew that catchers could work umpires, but this is huge. And there isn't really a lot of reason to doubt the data: the sample sizes are huge, and statistically reliable (meaning, there is consistency of results, and not just a random walk). BP also did an external validity test with scouting, and it checked out.
If you accept the result, then McCann has to be the best signing by any team in the 2013-2014 offseason, right? It sure seems like it. He's a stealth MVP candidate, especially if his dead-pull swing takes to Yankee Stadium well like we're all expecting.