Over the past few decades we've come a long way in our effort to understand baseball more completely, but for all the great advances sabermetricians have made there is still a major component of the game that has eluded us: How do we quantify the defensive impact a catcher has on the game?
Tom Tango's study of how Expos' great Gary Carter compared to other catchers of his time in terms of passed balls and wild pitches allowed and Bojan Koprivica's extensive research expanding upon it yielded valuable information, but they only really provided us a piece of the complex puzzle that is catcher value. The effort to solve this puzzle inspired Jeff Sullivan of FanGraphs to consider the impact that expert pitch-framers like Jonathon Lucroy have on the game:
I pulled up the league-wide strike-zone numbers for 2013, which for some teams is one game old and for other teams is zero games old. Brewers pitchers threw just 158 pitches, and they were given eight more strikes than expected. The Yankees were also at +8, but over 191 pitches. The league as a whole is at -12 strikes over almost 4,000 pitches. Now, in one regard it’s beyond silly to look at one game’s worth of these statistics. The sample sizes are miniature, the contexts aren’t averaged out, and the home-plate umpires are all different. But just for the sake of having a discussion, look at some of those low called strikes for the Brewers’ pitchers. The Brewers had Lucroy behind the plate, and Lucroy managed to get his team a somewhat expanded zone.
Adding eight strikes over the course of just one game is definitely not an insignificant contribution. Imagine the amount of runs a catcher with the pitch framing ability of Jonathon Lucroy could save his team over the course of a season. The exact amount is a bit difficult to nail down, however. A few years ago, Dan Turkenkopf penned an excellent piece on the effect that close calls of balls and strikes have in terms of runs. As you might expect, Turkenkopf found that the value of close call going a team's way varies in different situations. (Dan separated his findings into just about every category imaginable, which could be very useful when attempting further research on this subject.)
Jonathon Lucroy's effectiveness in "stealing strikes" stems in part from his zen-like stillness behind the plate. As Jeff noted, when you examine video of Lucroy catching you'll find that, with the exception of his elbow, the rest of his body moves very little, if at all. This is a key component of framing. Lucroy's minimized movement decreases the likelihood of the home plate umpire noticing what he's up to. Lucroy's pitch framing efforts are baseball showmanship in it's finest form.
It would be interesting to find out if the approach employed by Lucroy is an innate skill possessed from birth by only the best defensive catchers or if it is a skill than can be taught to young catchers. If framing is a skill that contributes to minimizing the amount of runs a team surrenders, studying video of catchers like Lucroy and attempting to mimic their techniques would be extremely advantageous for young catchers.
The problem that arises in attempting to place an exact value on pitch framing (or the lack thereof) by catchers are the large number of variables involved. It's fairly reasonable to assume that some pitchers have a higher number of calls go their way than others for whatever reason.
In regards to Jonathon Lucroy, the numbers in 2012 didn't seem to suggest any significant improvement for the Brewers pitchers with him behind the plate. Examining the Brewers' game logs at FanGraphs, I found that while there was a slight uptick in the Brewers' pitching staff's K% in games that Lucroy caught, there was also a nearly equal rise in the staff BB% as well.
Determining how much a good defensive catcher (and what exactly it means to be a good defensive catcher) contributes to the success of a pitching staff could in some way alter our perception of the careers of pitcher's we previously held in high regard.