December 14, 2015

Rubbing Mud

Sano's Strikeouts

by Matthew Trueblood

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Miguel Sano had a thoroughly impressive rookie season for the 2015 Twins. In almost precisely half a season, Sano slammed 36 extra-base hits and drew 53 walks. He posted a .314 True Average and was worth 1.9 WARP, even as a relatively heavy-legged DH. Those encouraging stats, though, can’t erase the one that threatens to define Sano’s future—his 35.3-percent strikeout rate.

It’s possible that Sano can outslug his vulnerability to whiffs, of course, but he’d be the first player ever to do so. He’s not going to have substantial (positive) defensive value, he’ll never add runs with his legs, and in time, his BABIP skill is going to erode; it does so for everyone. There’s just one good reason not to worry too much about Sano’s strikeouts, and to believe he’ll rein that whiff rate in enough to sustain his rookie showing: the pitchers he faced while fanning so often in 2015.

We have a stat to measure the average quality of opposing pitchers for all hitters: Opponent RPA+ (runs per plate appearance, relative to the league average). It’s exactly what you’d imagine: OPS+, basically, for the aggregate set of the hurlers a player faced, weighted by the frequency with which he faced them. Sano’s Opponent RPA+ in 2015 was 94, meaning he faced a mix of pitchers six percent tougher than average. No one who took as many as 200 plate appearances had a lower Opponent RPA+. On the list of 15 pitchers Sano faced at least five times in 2015, you can find the names of Corey Kluber, David Price, Garrett Richards, Lance McCullers, Yordano Ventura, Carlos Carrasco, and Chris Sale. He faced Dallas Keuchel four times on a Sunday in September, and took a golden sombrero home to remember the day.

Take away Sano’s 51 plate appearances and 22 strikeouts against the pitchers I just listed, and you have a guy with 97 whiffs in 284 trips to the plate, for a 34.1-percent strikeout rate. That’s a more significant change than it seems, and here’s why:

Player Seasons with 300 or More PA, MLB History (since 1901)

Forgive the numbers their imperfections: I’m drawing an arbitrary dividing line within small samples here. You can see, though, that Sano’s success in 2015 is an historical anomaly, whereas if he could trim his whiff rate even a few points, history would be on his side. (Okay, that’s misleading. Obviously, the majority of batters who strike out at least 30 percent of the time never get 300 plate appearances in a season, so the ones who do are a selected set of those teams believe can succeed despite that problem. It seems safe, though, to assume that Sano can be one of those special players.)

We can’t (and won’t) just toss out the times Sano faced the toughest pitchers, of course, because it’s not like they’re going away any time soon. Since he accomplished what he did while facing harder pitchers to hit than any other batter in baseball, though, we can at least offer the benefit of the doubt, until Sano proves that he can keep his strikeouts under control—or that he can’t. In a world that offers a half-dozen fairly reliable public sources for park factors, that delivers metrics that estimate players’ skills if they’d had a bit more or less luck on batted balls, and that gave us this, the adjustment we do least well these days is for the opponents against whom players accumulate their statistics.

Quickly, to the flip side: Travis d’Arnaud had an Opponent RPA+ of 110 in 2015, the highest among hitters with 200 or more trips to the dish. The Mets’ young catcher faced nine pitchers at least five times apiece: Tom Koehler, Williams Perez, Aaron Harang, Shelby Miller, Max Scherzer, Stephen Strasburg, Jerome Williams, David Buchanan, and Chris Rusin. Three of those guys are pretty darn good, but the other six illustrate the impact playing nearly half of one’s games against four opponents can have. The 2015 NL East may have been the weakest division baseball has seen in a decade, and several players’ stats within that division are distorted by the extremely uneven level of competition they faced. This should only mildly temper your enthusiasm for d’Arnaud, who can hit and is one of the game’s best framers, and so, is a superstar when he’s healthy. It’s mostly an observation: one thing Opponent RPA+ helps to underscore is just how absurd (though, very probably, necessary) the unbalanced schedule is.

Matthew Trueblood is an author of Baseball Prospectus. Follow @MATrueblood
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