It wasn't long ago that things weren't looking great for Evan Gattis and his prospects with the Astros. As a DH-only hitter who just wasn't hitting enough to be the DH (a below-average 99 wRC+ in 2015), it's little wonder many fans began to sour on him as a player. Throw in the first few weeks of his season being blown up by an injury, and it was easy to write him off, or at least not have any real expectations.
Something unexpected happened, though; with Max Stassi dealing with his own injuries and Erik Kratz posting a negative wRC+ at the dish, the Astros decided to have Gattis catch again. Gattis, of course, was primarily a catcher with the Atlanta Braves in 2013 and 2014, working 1,148.2 innings in the armor for the club before being traded to Houston.
It's hard enough to judge catcher's defense at all. It's harder still in such a small sample size. For what it's worth, DRS says Gattis is slight-above-average, and StatCorner's metrics like him as an above-average framer in a still-small sample. The eye test says he needs to do a better job of blocking balls in the dirt, and the framing could still use some polish, but that he's been solid overall.
And all of that is good, but the question isn't how has he done, but how will he do in the future. Is what he's done so far predictive? That's the question the Astros need to answer. Jason Castro has become one of the premier pitch framers in all of baseball; after being -29 calls in 2013, he's been one of the 15 best catchers in the Majors each of the last three seasons in that metric, and is currently in third this year, behind only Buster Posey and Yasmani Grandal.
The other wrinkle is this; Castro is actually producing at the plate this year. A 103 wRC+ isn't sexy in a vacuum, but it's darn good for a catcher. To wit; among all catchers who have at least 120 plate appearances, Castro is currently sixth in wRC+. When you throw in the defensive excellent as well, the argument can easily be made that Castro has been a top five catcher this year, at worst. But again, is that predictive? Castro is going to cost a lot as a free agent. He'll be worth it, based on past performance, but will he be worth it to the Astros? We're talking about a soon-to-be 29-year-old catcher with multiple knee injuries in his past who's having a nice showing at the plate in a walk year. There's plenty of risk there.
We know Gattis will hit, by which we mean he'll hit at least as well, if not better, than Castro is. You won't be losing anything on offense if Gattis is your starting catcher next year, and you may be gaining something, even. Gattis also has two years of club control remaining, so he'll be the more affordable player. It comes down to the defensive side; if Gattis can match what Castro does behind the plate, it would be foolish to even think of resigning Castro. Most people likely don't think Gattis will ever be that good, though looking at guys year by year with the framing metrics we have will tell you that there's a high level of year-to-year variance in those numbers, so it wouldn't be wise to write Gattis off as an elite future framer either. But whether he can be a future elite framer isn't even the question, either.
You have to decide how much framing means to you. How important it is, and how you can quantify it accurately. At this point, we know it's important, but we don't know how important, not in the way we need to. We know what the difference between a .300 OBP and a .370 OBP is beyond just the obvious numerical difference. We know what it means in terms of on-field value at a glance; a guy with a .300 OBP is mediocre, only to be used regularly if he provides significant defensive value at a premium position like shortstop; a guy with a .370 OBP is a guy you find a way to get into your lineup, other considerations be damned.
We don't have that with pitch framing. How much improvement does Gattis still need to make in order to equal Castro's overall value? How big of a gap in defensive value are you willing to suffer for the difference in price and risk? Those are the questions that need answering.
What we can say with reasonable certainty is that the Astros like Gattis as a catcher. They may not love him but they like him; they wouldn't play him back there if they didn't. When Stassi went down, they went out and got Kratz. They traded a prospect for him and played him with fair regularity. Playing a guy like Kratz is a sign to the world that you're willing to sacrifice offense for defense at the position, I.E. that you demand defensive competency first and foremost. So we have to assume they think he's at least competent back there. The comments from the pitchers who have actually thrown to him this year back that up as well.
If Gattis can show enough to the Astros' brass that they're comfortable with him being the everyday catcher moving forward, then they won't have to worry about the off-season; Gattis will be the man until the end of 2018. If not, they're in a pickle; their front-line catcher will likely walk, with no obvious internal solution present, and the guy who could have been that solution probably isn't a good enough hitter to be the DH, either.