Brayan Pena as an upgrade over Tony Cruz

From 2009 to 2013, Cardinals catcher Yadier Molina played in 689 games, 25 more than any other catcher in Major League Baseball (future Molina backup A.J. Pierzysnki ranked 2nd). He tallied 403 innings, the equivalent of nearly 45 complete games, more than Orioles backstop Matt Wieters, the second-most prolific backstop in that time frame.

Molina established a reputation as one of baseball's most reliable, durable catchers. And as he transitioned from a merely passable offensive catcher with an elite glove to being a truly potent bat while maintaining his sterling defensive reputation, the club's desire to play Molina as often as possible increased.

But in 2014 and 2015, Yadier Molina took a significant step back from his MVP-caliber 2012 and 2013. The 2014 version of Molina was slightly above average offensively but he missed 40 games due to a right thumb ligament injury, and in 2015, Molina started 136 games, as many as he had started in 2013.

But he was still not able to avoid injury: after starting 136 of the first 149 games of the season, Molina suffered a torn ligament in his left thumb. He missed the remainder of the regular season and returned for the NLDS, where he was briefly ineffective before exiting Game 3 after a re-aggravation of his left thumb.

Yadier Molina will turn 34 in July. He won't quite be an old man, but at a position as demanding as catcher, Molina will ideally be subject to less wear and tear throughout the season. And over the last few seasons, the presence of Tony Cruz seemed to hamper the team's progress in the department of giving Molina some much-needed rest.

My first post at VEB was about the return the Cardinals received from the Kansas City Royals for Tony Cruz, namely my amazement that Tony Cruz garnered a return at all. Cruz was sub-replacement level in each season since 2013 and the Cardinals desperately needed an improvement to back up Molina, hence the team's acquisition of Brayan Pena two days before dealing Cruz.

On the surface, Pena is an upgrade.

Certainly, nobody would confuse Brayan Pena for Yadier Molina, but particularly at the plate, Pena is a considerable improvement over Cruz. Defensively, however, it appears that Pena is worse than Cruz. Not to such a degree that he is not still a better overall player by Wins Above Replacement, mind you, but still worse. Here is how the two compare by conventional catching fielding metrics.

The two were certainly similar. But this is only a surface level interpretation of each's defensive acumen. Many anecdotes are given ascribing elite intangible qualities to Yadier Molina's defense (his ability to handle young pitchers, his ability to call optimal pitches for pitchers), but having never met Molina, Cruz, nor Pena, much less pitched with one of them at catcher, I wouldn't feel confident attesting to it.

But aside from anecdotal evidence, Baseball Prospectus has developed new statistics in recent years to deal with previously un-and-under-quantified catching skills, notably framing (the ability to deceive umpires into calling pitches outside the strike zone as strikes due to how the ball is caught). Here is how Tony Cruz and Brayan Pena compare by Baseball Prospectus catcher defense metrics, and just for perspective, how Yadier Molina fares.

Without question, Molina is the best of the three. He is by far the best framer, by far the best blocker, and by far the best at patrolling the basepaths. But while Pena isn't likely to start competing with Molina as the team's top defensive catcher, he does mark a noticeable improvement over Tony Cruz.

Pena is an average blocker and although he is not an exceptional framer, if the Cardinals' backup were to play 400 innings in a season and have about 3000 framing chances, he would be worth about -0.37 framing runs based on his previous three years' data, and Cruz would be worth about -2.97.

While a difference of 2.6 runs may seem immaterial, going with the general rule of thumb that a "win" requires 10 runs (since scoring has declined recently, this may be an exaggeration, but let's just say it for simplicity's sake), framing alone is worth about $2 million on the open market.

Given his easily noticeable offensive improvement and that there is little reason to believe that the more experienced Pena is any worse than Tony Cruz at handling young pitchers, Brayan Pena appears to be a noticeable upgrade at backup catcher. And looking at new catching stats, the upgrade appears larger than previous generations may have assumed.