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The hidden reason the Yankees might not want to start Masahiro Tanaka in the Wild Card Game

The A’s make for a subtly difficult matchup for Masahiro Tanaka.

Chicago White Sox v New York Yankees Photo by Rich Schultz/Getty Images

The auditions for the Yankees’ starter in the Wild Card Game are all but complete. By tomorrow, each of New York’s top three starters, Luis Severino, Masahiro Tanaka, and J.A. Happ will have submitted their final starts for consideration by manager Aaron Boone. What’s done is done, and all that’s left is for Boone and his staff to decide upon a strategy for the fateful one-game playoff.

For a stretch, Tanaka looked like the favorite to start. Severino was struggling mightily, and Tanaka was on fire, with a better pedigree than Happ. Tanaka was off in his final start versus the Rays and Severino has looked much better lately, decreasing the odds of a Tanaka Wild Card start. Still, there’s a subtle reason the Yankees might want to think twice before tabbing Tanaka to start his second Wild Card Game in four years.

Tanaka is a very good pitcher. Perhaps the biggest reason that Tanaka excels is his proclivity for getting hitters to swing at pitches they can’t hit. The easiest way to generate empty swings and weak contact is to force hitters to offer at spinning breaking balls and fading offspeed pitches out of the strike zone.

Almost no one is better at that than Tanaka, who is armed with excellent secondary pitches and strong command. There have been 137 pitchers who have tossed at least 100 innings this year. According to FanGraphs, only one pitcher has generated a higher rate of swings on pitches out of the zone than Tanaka: possible NL MVP Jacob deGrom. Opposing hitters swing at Tanaka’s pitches out of the zone nearly 38 percent of the time. All those bad swings have allowed Tanaka to post one of the top ten swinging strike rates in all of baseball.

Using his slider and splitter to get hitters to chase is both Tanaka’s bread and his butter. Per Baseball Savant, the league as a whole posts a .288 wOBA when putting the ball in play on a pitch out of the zone. Tanaka allows a .226 wOBA when allowing a ball in play on a pitch out of the zone. When he yields a ball in play on a pitch in the zone, Tanaka allows a .424 wOBA, compared to a .388 wOBA for the league. Tanaka simply must induce swings on bad pitches to thrive.

That’s where the Athletics come in. The A’s will be the Yankees’ opponent in this year’s Wild Card Game, most likely at Yankee Stadium. Tanaka would have to get the A’s to chase his slider and splitter, rather than hone in on his weak fastballs, to have a successful start. The A’s are uniquely situated to not let that happen.

Almost no team in the majors lays off pitches out of the zone more than Oakland. They have posted a 28 percent chase rate, second lowest in the majors, and nearly ten points lower than the chase rate Tanaka has generated this season. The A’s have also swung at pitches in the zone at a top-ten rate. They are among the most disciplined teams in the entire league.

That’s a bad matchup for Tanaka. There might not be another pitcher in the game that relies more on opponents expanding the zone, and there is hardly another team in the league that expands the zone less than the A’s. Scanning the roster’s individual chase rates, eight of Oakland’s most likely nine starters have posted rates below the league average. Stephen Piscotty is the only hitter likely to start that has swung at pitches out of the zone at an above average rate.

Anything can happen in one game. Give a pitcher a scouting report that says the other team crushes cutters, and that pitcher will say “Well, they won’t crush my cutter”. Maybe Tanaka could match up with the disciplined Oakland lineup and make them crack. Tanaka is good, and his slider and splitter are great pitches.

Even so, starting him feels risky. It’s easy to envision the A’s spitting on sliders in the dirt and outside offspeed pitches, waiting on Tanaka to come in the zone with a straight four-seam fastball. To get a sense of what such a start could look like, I looked at Tanaka’s outings in which he posted his five lowest chase rates on the year. In those outings ,he lasted less than five innings per start, indicating his opponents’ patience drove up his pitch count. He posted a 6.34 ERA in those starts.

If Tanaka faces a lineup that waits him out, the most likely outcome is a five-ish inning start with three or four runs allowed. That’s not terrible, but it’s certainly not what the Yankees are looking for in an elimination game. Tanaka is a fine pitcher, and a crucial part of the Yankees’ staff. If the Yankees are to go deep in the playoffs, Tanaka will need to pitch well. It just doesn’t seem like he matches up with the Yankees’ Wild Card foes.