Masahiro Tanaka can still be an ace for the Yankees

At times, Masahiro Tanaka’s arc with the Yankees has been odd. He burst onto the scene in 2014 and dominated for the first few months, turning every start into an event. A partially-torn UCL then fell him, casting a pall over his season. Whispers of Tommy John surgery would follow him at every turn.

Even so, Tanaka kept pitching. Sometimes he reached the brilliance he showed during his debut campaign. Other times he looked lost, like when he ran an ERA over 6 for the first couple months of 2017. For good measure, Tanaka decided against exercising an opt-out clause in his contract after 2017, staying in New York when many supposed that he would at least leverage his opt-out to negotiate a new deal.

It’s been a strange route for the 30-year-old to settle in as essentially a very good second or third starter. Last year, Tanaka wasn’t able to recapture the heights of his most excellent seasons, 2014 and 2016, but he bounced back nicely from his trying 2017. He posted a 3.75 ERA, good for a 116 ERA+. He struck out 159 batters and walked just 35 across 156 quality innings.

Yet even in posting a strong season, Tanaka’s 2018 left me wondering: could Tanaka ever be an ace again? Could he ever ascend to the heights that he reached back in 2014 and 2016?

To try to get an answer, let’s take a look at what made Tanaka’s best seasons so special, and whether the component parts that helped him then still exist now. In many ways, what helped propel Tanaka in 2014, when he posted a 138 ERA+ for the year, including a 2.27 ERA before injury, and in 2016, when he ran a 140 ERA+ and generated down-ballot Cy Young support, is still around today.

For one, Tanaka still generates swings on bad pitches more than ever. Here’s his out-of-zone swing rate by year, courtesy of FanGraphs:

Tanaka has always run sky-high chase rates, and the past two seasons have been no exception. Consequently, as he’s continued to get hitters to chase, Tanaka has continued to post contact rates as low as his debut year:

His groundball rate has stayed pretty much constant, for the most part hovering between 47 and 49 percent every year of his career. Plus, given that he’s still only 30, it’s not shocking he’s mostly retained his velocity. Check out his year-over-year pitch velocities per Brooks Baseball:

He saw a tiny dip last season, but Tanaka can throw almost just as hard as he did when he entered MLB. So what gives? Every metric we’ve checked so far has shown that Tanaka still has what he debuted stateside with. He’s still generating lots of swings and misses on heaps of pitches out of the zone. He’s still running high groundball rates, and he hasn’t lost velocity.

Rather, where Tanaka excelled in 2014 and 2016 and has struggled elsewhere is in contact management, and in particular, managing the long ball. In 2014 and 2016, Tanaka posted home run per nine rates just below one. That rate was 1.46, 1.77, and 1.44 in 2015, 2017, and 2018, respectively. He posted a 14 percent HR/FB rate in 2014, and a 12 percent figure in 2016. That mark ballooned to 21 percent in 2017, and about 17 percent in 2015 and 2018.

The primary difference between Tanaka’s seasons when he’s been an ace and the seasons in which he’s been merely good is his ability to limit hard contact and keep the ball in the park. Statcast doesn’t have figures dating back to Tanaka’s 2014 season, but in 2018, batters posted a .375 xwOBA on contact versus Tanaka, and an eye-popping .403 figure in 2017. In 2016, batters only managed a .348 xwOBA on contact, indicating that they had much less success when they actually struck the ball against Tanaka.

Tanaka’s unimpressive fastballs have driven his struggles suppressing good contact. Last season, opposing hitters posted wOBA’s above .400 against both Tanaka’s four-seamer and his sinker. They posted wOBA’s above .420 on both pitches in 2017. In 2016, Tanaka limited hitters to a .277 wOBA with his sinker, and a .340 mark in 2014.

This trend holds up even when we look at Statcast’s expected stats. Again, we don’t have access to data in 2014, but check out this chart showing Tanaka’s xwOBA allowed broken down by year and by pitch group:

Tanaka did a great job limiting quality contact with his fastballs in 2016, only to see hitters brutalize his heaters in the past two years. Conversely, Tanaka has suppressed offense in a highly consistent manner with both his breaking and offspeed pitches.

The delineation is clear, and fairly intuitive: when Tanaka is limiting homers and hard contact against his fastballs, he’s an ace. When hitters are crushing four-seamers and sinkers in the middle of the zone, Tanaka can still perform at a high level, but profiles more as a number two.

That being said, I think this conclusion supports the idea that Tanaka could very well still be an ace, provided he stays healthy. He’s keenly aware of the damage hitters do against his heaters, as he’s severely curtailed his fastballs’ usage rates in recent years. Tanaka knows his weakness, and if he can further adjust, either by throwing even more of his superb splitter and slider, or by somehow finding a way to improve the performance of his heaters, then ace-caliber performance is eminently in play.

This contributes to the sneaky upside of this Yankees rotation. Tanaka, Luis Severino, and James Paxton all carry their own questions marks, but they all also clearly have the ability to pitch like aces. In the unlikely-but-possible event that they all do, the Yankees could have a rotation for the ages.