BOSTON -- It's often been said that defense is the final frontier of analytical assessment of baseball. And if that's true, then catcher defense makes up the very furthest reaches of that frontier. But analysts are decoding more and more of the mystery of catcher defense, and a paper presented Friday at the annual Sloan Sports Analytics Conference took another step in that direction.
In recent years, pitch framing has become a popular topic among people who study defense, with the idea being that some catchers have a particular skill at "stealing" called strikes on pitches that are on the border of the strike zone. Joe Rosales and Scott Spratt of Baseball Info Solutions argue, though, that the catcher is not the only variable.
Rather, while catchers certainly are important, umpires, batters and pitchers all have demonstrated consistent influence on what percentage of borderline pitches are called strikes. It's more pronounced for catchers than for batters or pitchers, but the influence is still there.
"All of their actions influence whether or not that pitch is called a strike," Spratt said. "What we set out to do with our system is to create a framing methodology that actually apportions credit for all of those parties."
Per their methodology, which like many other metrics measures players in terms of runs saved or lost, the gap between the best and worst catchers at framing pitches comes out to a little more than 30 runs per year. The best, Mike Zunino and Hank Conger, saved 16 runs each in 2014. The worst, Dioner Navarro and Jarrod Saltalamacchia, "saved" negative-17 and negative-16 in 2014.
Compared to hitters and pitchers, the effect is large. Hisashi Iwakuma was the best pitcher at "stealing" strikes in 2014, getting four runs' worth of benefit, while Nathan Eovaldi lost three runs. It was similar for hitters, with Dustin Pedroia being four runs to the good and Melky Cabrera three runs on the negative side.
The range of umpires was somewhere in between, according to Spratt and Rosales, with three umpires totaling 12 runs worth of extra strikes in their games. One, Paul Schrieber, made calls that benefited hitters to the tune of 16 runs, but no other umpire ranked higher than nine runs to the hitter-friendly side.
Matthew Leach is an editor and reporter for MLB.com. Read his blog, Obviously, You're Not a Golfer and follow him on Twitter at @MatthewHLeach. This story was not subject to the approval of Major League Baseball or its clubs.