February 27, 2014

Skewed Left

What it Means to Move Off Catcher

by Zachary Levine

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One of the favorite storylines this time of year is the positional change, whether it’s putting on an entirely different kind of glove or just moving over a few dozen feet to the left or right. Predicting performance changes is hard, but a positional change is something we can see, so it’s something we can write.

One of the least-favorite storylines—or at least most confusing—is when a positional change comes with a promise that the player will be able to improve on offense because he can spend more time working on it.

You’d think this would be particularly true with catchers. Shortstops, for instance, spend as much time taking ground balls as their counterparts down the defensive spectrum at second and third do. But if this were ever going to be true, you’d think it would be with catchers. Every day before the game, while the other position players are taking extra hacks in the cage—which may or may not help, granted—the catchers are sitting in with that day’s starting pitcher and the pitching coach going over the opposing lineup.

This winter, we learned that a couple of long-rumored moves were going to finally happen. In the much longer-rumored instance, Joe Mauer isn’t listed in the top four of the Twins’ official site’s depth chart behind the plate. He’ll be the starting first baseman and will presumably DH from time to time as well. Then there’s Carlos Santana, whom the Indians will move to third base with Yan Gomes taking the majority of the crouching.

Baseball doesn’t provide a ton of history of such moves to analyze whether they have any immediate impact on offense, and beyond that, the confounding variables present a problem. A move from behind the plate can come not for prevention, longevity, or defensive purposes, but as a direct result of an injury that we’d expect to see the player bounce back from on offense as well. So in looking at the predecessors of Mauer and Santana, neither of whom has been without injury concerns, we limited it to those with at least 70 games behind the plate the year immediately before the move.

As a result, there’s really not a lot of history to look at. In fact, there was a 14-year period leading into the WARP era in which nobody fit the category. But since 1958, there have been 68 qualified players who played the majority of their games at catcher and switched the next year to play the majority at another position (not pinch-hitter or pinch-runner).

Where did they go? Mostly where Mauer is headed. A few to the other corner or DH. A few to the corner outfield spots, and of course one future Hall of Famer to second base.

So all of them moved to positions where more offense would be expected, but of course they were still the same players. Now, you may have thought that their offense would improve as a result of having the hardship lifted, as I did, or you may have thought they’d decline because hey, these are often old guys who can’t handle catching anymore, and that’s what old people do—they decline. Either way, you would have been wrong. Offensively, on average, they stayed exactly the same.

A .266 true average before. A .266 true average after.

And they stayed pretty true to their aging curves as well. Offense for catchers has tended over the last five decades to peak at 28.* As players aged closer to that peak, their TAv tended to go up, in line with what we’d expect. As they aged past it, their true averages went down, as you might expect from an aging player. So that’s some explanation for why with younger players, the drop in positional value was somewhat masked, whereas in the 29-and-older set, a move off catcher has tended to be synonymous with a plunge in value.

*Actually, the highest TAv for catchers is at age 42, and there are other local maxima at 21 and 40, but there’s some extreme survivor bias (the 42s) and selection bias (the 21s) there.

The full breakdown is as follows. (One thing to note: Average playing time was almost identical before and after moves off catcher, so the positional adjustment is largely responsible for the decline in value.)

What was most surprising, though, were the numbers in each group. Moving off catcher has not historically been reserved for the oldest players. The median age to move is between the age-28 season and the age-29 season, and this doesn’t even count the Wil Myers or even Bryce Harper types who just gave up on catching before getting to the majors. The modal age is a year younger.

For every Mike Piazza, who despite never being a great defensive catcher (by traditional metrics, if not more advanced ones) didn’t vacate the position until age 38, there is a Biggio, who was moved off it quickly. For every Jorge Posada, who was the oldest player on the list ever to move off catcher, going to DH at 39, there is a Todd Zeile, who didn’t last past his age-24 season at the position. Zeile was sixth in rookie of the year voting as a catcher in 1990 and then never played it again for a single game until he was a 38-year-old Met in 2004 – his second go-around with one of his 11 teams.

With true average normalized around .260, the move off catcher is not only done with young players, but it’s done with young players who play a lot with below-average offense, moving them to positions where more offense is required. And that feels like the most surprising part. The young players aren’t even the Myerses and Harpers. They’re not even the Santanas (the Santana in question had a TAv of .305 last year). And if they respond, it’s often just the natural progression of the aging curve.

At least for catchers, there seems to be very little to a player’s ability to improve just by concentrating on the bat.

Zachary Levine is an author of Baseball Prospectus. Follow @zacharylevine
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