For years now, analysts have tried to gauge just how valuable catchers are in regards to improving (or hurting) a pitcher's performance. Many of the measures invented, such as Catcher's ERA, do not capture what it is that backstops do, but they are stepping stones on the path to understanding true catcher value.
Many of those who have worked to improve this understanding now work for major-league teams -- this is an area new and unknown enough that baseball clubs themselves want in on the innovation. Keith Woolner was hired by the Indians, years after working to make catcher stats more meaningful. Mike Fast, also of Baseball Prospectus, is now with the Astros, in part due to his fantastic progress in measuring catcher value in framing and pitch blocking. Sean Smith, Dan Turkenkopf, Bojan Koprivica, and Max Marchi have also contributed greatly to this quest, and now, we have a pretty good idea of how to measure the effects of what catchers do defensively.
The Red Sox used to have it great in this regard. Jason Varitek was one of the best out there at blocking pitches, and even better at game calling, which some -- like Dan Turkenkopf -- believe is the biggest single aspect of catcher defense. How big? For his career, by wins above replacement, Varitek had negative defensive value thanks to his inability to throw out opposing baserunners. Since the various Win models don't include all the aspects of catcher defense that have been researched in the last few years, they paint an incomplete picture of catcher value.
Now, if you include what Varitek was valued at for pitch framing, pitch blocking, and the like, rather than the three wins he was worth from 2008 through 2011, he now comes out to eight. That's a huge difference, one that makes Varitek an average player over the last four years of his career, at a time when many thought his decreased abilities were making him a liability.
Why bring all of this up now? To help explain what it is the Red Sox didn't have in 2012. Using the same measures (and once again, the data of Max Marchi) we can see how valuable Boston's backstop tandem of Jarrod Saltalamacchia and Kelly Shoppach were. Salty graded out at exactly zero for catcher defense -- nothing gained, nothing lost. This was an improvement from the past, likely from not having to catch knuckler Tim Wakefield anymore. Combined with his wins above replacement, that makes Salty a two-win backstop. Like Varitek, that's average, and it's what we thought Saltalamacchia was.
Shoppach, though, was replacement level before accounting for Marchi's catcher defense. He hit well, but didn't play constantly, keeping him from either producing much or causing too much damage with his poor catch-and-throw skills. Those weren't his only issues while in catcher's gear, though: Shoppach was awful at framing, and a non-factor with pitch blocking. All told, Shoppach actually cost the Red Sox a win above replacement in 2012, despite his only playing in 48 games. Combine the two, and throw in Ryan Lavarnway's awful month-plus, and you have the Red Sox backstops essentially putting up a cumulative replacement-level effort. That's a long way from seeing Jason Varitek put up a couple of wins by himself despite being a part-time player.
That brings us to the David Ross acquisition. Ross has a reputation as a fine defensive catcher, one who can call a good game, one who can throw out would-be basestealers. He can also hit, and might be the top option offensively that the Red Sox have behind the plate. He played in 62 games in 2012, valued at a win above replacement before factoring in advanced catcher defensive measures. After adding those in? Ross was worth somewhere between three and four wins. In just 62 games. For context, according to Baseball-Reference, Dustin Pedroia was the lone player on the 2012 Red Sox to surpass three wins of value (blowing it away with nearly five), while Adrian Gonzalez and David Ortiz matched it in their partial seasons. It might be hard to accept, but catchers deserve a ton of credit for their work, even backup catchers.
This credit goes to the pitchers currently, be it for good or bad. Shoppach was poor at framing, poor at blocking -- this has an effect on what a pitcher can successfully throw, as a lack of blocking ability means spiking a slider low in the strike zone is dangerous, and poor framing means living on the edge of the strike zone could result in too many walks. Shoppach doesn't get the blame for this in the end, though, as it's the pitcher who sees his ERA inflate, or his K/BB diminished. These advanced catcher metrics put more of the credit where it belongs, and given just how much credit David Ross historically gets, that's a good thing for the Red Sox pitching staff.
Ross is by no means the only catcher recognized for his particular talents. The Brewers locked up Jonathan Lucroy for years, at a rate that, when you account for the impact he has on the team defensively, is a total steal for Milwaukee. Yadier Molina was a legitimate MVP candidate even before his bat developed to the point where the masses would accept him as such. Jose Molina might be the best defensive catcher ever thanks to his absurd ability to frame pitches and help out his moundsmen. Ross is Boston's answer to that, the first viable solution to replacing Jason Varitek that the Red Sox have been able to bring in.
Saltalamacchia might not be around on the 2013 Red Sox, leaving things to Ross and Lavarnway. Boston could go out and sign Mike Napoli to play first and backup behind the plate, and Napoli, for all the complaints about his defense, rates better than Shoppach there. Regardless of the combination, the catching will likely be better in 2013 -- much better -- and both the lineup and pitching staff will improve because of it.