Let’s say you took over a baseball club with a recent history of some severe struggles. The main culprit, it appears, is pitching—only a handful of pitchers have broken through for the team in recent memory, and most have done quite a bit worse than expected. The fact that many pitchers have struggled at the same time has caused a cascade of other issues because starters don’t get far into games: the vulnerable underbelly of the bullpen has been exposed, and shuttles to and from the minors became commonplace. Not only were pitchers faring unexpectedly poorly, but the club has had to rely on its worst pitchers more often than other clubs—and those worst pitchers have fared unexpectedly poorly, too.
That’s the situation in which GM Mike Hazen and his new staff have landed in Arizona, and by trading for Taijuan Walker last week—who may be particularly well positioned to handle a transition to the D-backs staff—Hazen sent a strong signal that he was aware of the problem and the need to address it. In opting not to tender a contract to Welington Castillo last night and in signing the erstwhile Jeff Mathis to a free agent deal, Hazen sent another strong signal: that he does not believe this pitching problem can be solved merely by changing up the staff, or by changing current pitchers’ approaches.
There’s no reason to assume that Mathis will be the D-backs’ primary catcher next season, but say for the sake of comparison that either could have played 120 games for the team in 2017. Castillo has been just a bit below average at the plate in recent seasons, but that’s a fairly rare find at the catcher position; over 120 games, you might guess he’d add about 55 runs (as in, weighted Runs Created) to the D-backs’ effort, a far cry from the 35 to 40 runs you might expect from Mathis in the same span.
Behind the dish, though, the story is a bit different. Castillo has steadily improved from a nightmarish 2013, but even with that improvement, he cost the D-backs 9.8 runs relative to the average catcher, just with framing, in a little under 120 games played. He added some value back with his arm, finishing at -7.3 Fielding Runs Above Average in 2016, per Baseball Prospectus. Call it -7.5 for our comparison. Mathis was worth 7.5 FRAA last season, after adding 7.5 runs with framing skill and rating average in other defensive skills —but that was in just 41 games, many of which he shared time. Back of the envelope, that’s something in the order of 22 runs better than the average catcher, and just about 30 runs better than Castillo.
A downgrade offensively of 15 or 20 runs, but an upgrade defensively by 30. Sounds like a good trade, especially considering Castillo was due something like $5.9M in arbitration for 2017, and Mathis was inked at $4M total for 2017 and 2018. As a swap, this doesn’t even account for the catchers’ relative skills in pitch-calling or handling of pitchers, something I’m not equipped to value. It seems to me, though, that after working in Boston, Hazen is somewhat equipped to do that, and it seems to me that Castillo probably wasn’t an amazing catcher in that way. Chances are, it only widens the Mathis-favoring gap, rather than narrowing it.
You don’t need to believe me that Mathis is probably worth 0.1 runs per game more than Castillo (although you should) to get behind this exchange, though. To believe the team has done something smart here, you only need to return to that hypothetical that we started with.
For Arizona, hitters who have fared differently than expected have tended to do better than expected, from Paul Goldschmidt to Ender Inciarte to Luis Gonzalez. It’s not a stretch to connect better hitting with consistently underwhelming pitching efforts, and yet, because the pitching problems “cascade,” it’s likely that improving the D-backs defensively is more important than improving the D-backs offensively. That would cause you to consider changes that would affect all pitchers, even if they also affected all hitters.
All ballparks are different, but Chase Field is strange in a way that only Coors Field is also strange. Usually, a large outfield will lead to more hits (and more hits being doubles or triples), but fewer home runs; a small outfield will lead to more home runs, but fewer hits overall with outfielders asked to cover less territory. Like Coors, Chase defies this general rule. Chase Field is neutral in terms of home runs, but hitters still get the hits- and doubles-promoting benefits of large dimensions. That’s why a hitter who bails for home runs like Mark Trumbo isn’t a good fit at Chase—he’s not making use of any special Chase benefit, but he’s also failing to cash in on the large outfield dimensions with a low contact rate. That’s why line drive hitters like Goldschmidt and Jake Lamb should be expected to do well—they’ll cash in on the large outfield with doubles and triples, but without costing themselves home runs, necessarily.
That’s also why Chase Field is a pitching hellhole, particularly with Coors in the same division. If the priority is to help the pitching, even at an equal offensive cost, what are the options? There’s always the humidor possibility. You could also change the Chase Field dimensions, although the only way that would work would be by raising outfield fences, and that wouldn’t help very much. Is there anything else that would combat the oddity that is Chase Field?
Just catching. Opting for a glove-first catcher would shift some offense to defense, theoretically taking pressure off of the pitching staff, and theoretically going some way toward stopping that “cascade” in which pitching problems have multiplied. Even if the tradeoff were negative overall, you’d still have to consider it. Mike Hazen’s first and most important task is to determine whether Arizona can be a vaguely hospitable place to pitch, after so many experiments and so many pitchers have failed. Compared to using a humidor (a process that probably could not be reversed) and raising fences (expensive, not especially effective and hard to reverse), switching catcher personnel seems pretty easy, right?
Mathis over Castillo is a serious downgrade at the plate, but an even more serious upgrade behind it. On top of that, helping the pitching staff to the maximum extent possible is wise, particularly when that can be done without compromising the success of most of the batting lineup. What’s not to like? As surprising as the Castillo non-tender and Mathis singing were, it sure looks like Hazen has exactly the right priorities, and this is almost a no-lose proposition. If Mathis performs as expected, he may represent an upgrade over Castillo on a game-per-game basis; but even if he falls short, chances are he will help the team get more, better innings from its better pitchers.
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FanGraphs Stats Glossary
Nick Piecoro Author Page
Cot's Baseball Contracts
BP Base Running Stats
Previously on The Pool Shot, the guys explained some of their favorite advanced stats. Hitting, including wRC+, HHAV and batted ball; pitching (38:00), including FIP, xFIP and SIERA; and baserunning and defense, including UBR, UZR and DRS (58:00).