Catcher Defense & the Great Yadi!
Defense “up the middle” is always discussed when the topic is the most important aspects of a baseball team. Having superior defenders at catcher, middle infield, and centerfield can cover up deficiencies at other positions and really make the pitching staff seem to perform better. It’s obvious that each middle defensive position requires completely different skillsets; center requires speed and proper route running technique while middle infielders require quickness and great hands. Catcher is the most widely misunderstood and difficult for the everyday eye to judge.
Catchers are in a separate world to themselves as far as defensive metrics and how to measure the value of catcher defense. There are a number of unique defensive skills that catchers need to posses, each skill having potential ability to impact the overall value a catcher’s defense: arm strength and accuracy, pitch blocking ability, pitch framing ability, and pitch selection. Each of these skills is much different from anything required of any other fielder, in my opinion, making it one of the most intriguing positions in baseball.
Many teams put a premium on defense at the catcher position, but catcher defense isn’t measured the same way as the standard defensive metrics. Fangraphs has a statistic called Catcher Defense that is used for the “Fielding” component in WAR for catchers. It takes two factors of catcher defense and combines them into one value:
rSB: Stolen Base Runs Saved measures how many “runs” a catcher contributes to their team by throwing out runners on the base paths and preventing stolen bases.
RPP: Passed Pitch Runs calculated the number of runs above or below average catcher is at blocking pitches.
The final two aspects of catching defense are difficult to isolate in a statistic. Pitch framing ability depends partially on the home plate umpire getting fooled, and calculating the reason the umpired calls a pitch a strike when it should have been a ball cannot only be credited to the catcher. Pitch selection becomes equally difficult to quantify. Regardless, rSB and RPP make a good way to measure catching defense, and like all defensive stats 0 is considered average and anything above 0 is above average.
It’s never a good idea to look at defensive metrics for one season, or even part of a season, to draw conclusions on a player, but for reference, Carlos Santana and Matt Weiters are tied for the lead with Stolen Base Runs Saved this season. Santana spent the offseason with Sandy Alomar Jr. reworking his defensive game, and it is obviously working. Over the past 20 years, Yadier Molina of the Cardinals has by far been the best catcher for both rSB and RPP. Biking for Baseball is looking forward to seeing the best defensive catcher in the game behind the plate at Busch Stadium tonight!