Nick Hundley and Tony Wolters have split time at catcher during the first half of 2016. In the second of a two-year contract, Hundley was the assumed starter; Wolters was a surprise. A waiver claim during spring training, Wolters broke with the team as the backup catcher. Due to a couple of stints on the disabled list for Hundley, Wolters has caught about as many games as the starter. As the Rockies prepare to begin the second half of the 2016 season, it’s not self-evident that the first half’s depth chart should carry over. There are a lot of reasons to give Tony Wolters more playing time.
Hundley and Wolters have obvious and opposite strengths and weaknesses. Wolters is much better defensively, which is evident just as much in statistics as it is in eyeballs. According to Baseball Prospectus’s advanced catcher metrics, Wolters has the advantage over Hundley in every measure, from blocking, to the running game, to framing. Cumulatively, BP suggests that Hundley has cost the Rockies two runs with his defense, while Wolters has contributed about five. The seven run difference—which is based on a half-season’s worth of work, remember—almost amounts to a full win separating the two from defense. Eyes and player reports support Wolters’s defensive acumen, and they also highlight the excellent rapport he has with the pitching staff.
Hundley has the advantage on offense, and it’s not particularly close. Hundley is hitting .254/.358/.446, which amounts to a performance at the plate about five percent worse than a league average hitter. Wolters is hitting .215/.296/.331, which is an astounding 48 percent below average. He’s demonstrated the ability to take a walk, but even with that skill his batting line still amounts to an OBP under .300 without any punch to compensate. If Wolters weren’t an extremely good defensive catcher, he probably wouldn’t have a major-league job.
There’s another way to compare Hundley and Wolters though. Notably, Hundley and Wolters have caught a similar number of innings this season, 325 for Hundley and 296 2/3 for Wolters. Given this similarity, how well have pitchers performed with each catcher? The answer is definitive, although the meaning of the answer is not. It’s Wolters, and it’s not particularly close:
|Innings caught||PA||Pitcher ERA||HR||BB||K||K/BB||BA||OBP||SLG||BABIP||tOPS+|
Caveat: the idea that a catcher can be given credit for the ERA of the pitchers he catches has mostly been rejected. Counterpoint: the 1.39 difference between the two in similar playing time is clearly worth dwelling on. An Andrew Miller separates them. While these things contribute to the difference in ERA, it’s also worth nothing the difference in walks and home runs. The difference in walks might be attributed to framing skill. Wolters’s receiving ability can mitigate walks and help the pitcher throwing to him.
The homer gap could be viewed as an example of game calling. Whereas pitchers working with Hundley have allowed a home run every 27.3 plate appearances, pitchers throwing to Wolters have allowed homers every 49.3 times to the plate. Perhaps this is an example of Wolters calling for the most effective pitch and location at the right time, and maybe that is a manifestation of the difference between the catchers in terms of internalizing hitters’ scouting reports. The difference in tOPS+ is another way of presenting the fact that pitchers have done better than usual (and batters worse) with Wolters behind the plate, and vice-versa for Hundley.
This is speculation about correlation—let alone a statement about causation—but the differences here are too large to ignore. At least they are right now. It’s possible that this is all noise, and things will even out in the second half. Even so, I’d be willing to put my faith in the noise and give Wolters a lot more starts for the remainder of the season (assuming Hundley isn’t traded). Unlike Hundley, Wolters will likely be around next season in some capacity. And maybe, just maybe, additional playing will help Wolters develop the bat a little bit. Because if he is able to do that, it would make any near future future playing time discussion easier for the Rockies.