Position previews: Catcher

AP Photo/David Zalubowski

A few days before general manager Jerry Dipoto made a couple of loud noises in the free-agent market, he made two lower-decibel moves that nonetheless resonated with Angels fans.

Dipoto traded young pitcher Tyler Chatwood to the Colorado Rockies for catcher Chris Iannetta and followed that up three days later by sending catcher Jeff Mathis to Toronto for pitcher Brad Mills.

Many Angels fans, tired of watching Mathis' feeble at-bats, seemed joyous over the news. But how much better -- if at all -- will it make the team? Are the Angels simply giving up defense to gain offense? Or, was Mathis' defense -- the subject of periodic rhapsodies from manager Mike Scioscia -- overrated? Is Iannetta even a much better hitter?

The first few questions are difficult, maybe impossible, to answer. Baseball analytics have come a long way in the last 10 years, but they come up short when it comes to breaking down a catcher's contributions to stopping the other team from scoring.

I got assistance from ESPN statistical analyst Mark Simon, who said what I suspected. There really is no good overarching measure of a catcher’s defense. Here’s what we have to go by:

Angels pitchers had a 3.25 ERA when Mathis was catching. Only Philadelphia’s Carlos Ruiz had a better CERA among guys who caught at least 80 games. They had a 3.86 ERA with any other Angels catcher.

Rockies pitchers had a 4.22 ERA when Iannetta was catching. They had a 4.84 ERA with any other Rockies catcher.

Summary: Both guys were slightly better than the on-hand alternatives at helping pitchers succeed, but we can’t even say that with certainty. What if they were better because they were paired with better pitchers? It’s not uncommon for a manager to give his best catcher a day off when the fifth starter is pitching, figuring that game is a crap shoot anyway.

But we can safely assume, probably, that both Mathis and Iannetta are good at catching and that Mathis is a little better than Iannetta.

What about throwing? Mathis caught 12 of 60 guys who tried to steal on him, 20 percent. Iannetta caught 26 of 96 or 27.1 percent. Iannetta had a better rate, but fewer guys tested Mathis. Then again, more teams try to steal bases in the National League, so what have we really learned? Both had below-average rates of catching base stealers, but is that because their pitchers either pay less attention to runners or aren’t as good at holding them on as other teams'?

Seems beyond inconclusive, maybe even meaningless. We can probably be safe in saying that neither catcher is outstanding at containing the other team’s running game.

What motivated this trade, of course, was hitting, primarily Mathis' lack of it. Among players with at least 200 plate appearances, only Minnesota's Drew Butera and Tampa Bay's Reid Brignac had a worse OPS than Mathis' .484. Only Butera, Adam Dunn and Tyler Colvin had worse batting averages than Mathis' .174.

By any measurement, the Blue Jays acquired one of the truly awful hitting catchers. Mathis' career batting average is .194, his career slugging percentage .301, both staggeringly low numbers.

Iannetta's primary asset as a hitter is his patience, a trait the Angels generally lacked before Dipoto took over. His career on-base percentage, .357, is more than 30 points above the league average, for catchers and non-catchers alike. He also has decent pop judging by a .430 slugging percentage.

The more troubling numbers arise when you poke around under the hood. Over the last three years, Iannetta batted .281 in Colorado and .171 everywhere else. Coors Field was the second-most hitter-friendly park in the majors last year. Angel Stadium was the fourth-worst.

He batted .256 against left-handers and just .213 against righties. Those numbers would seem to suggest a role for young switch-hitting catcher Hank Conger, who hit all six of his home runs against right-handed hitters last year and only had 11 at-bats from the right side.

Summary: Iannetta's offensive impact might be mitigated by changing teams, but even a modicum of offense will be a major upgrade over what the Angels have suffered through with Mathis.

We'll have a better sense of how everything is working out by May or so, based on pitchers' performances and their comments about working with Iannetta. But it looks as if Dipoto might have improved a woeful situation by doing some shuffling behind the plate.