What’s wrong with Masahiro Tanaka?

Masahiro Tanaka hasn’t pitched well this season. There’s no way around it. Through eight starts, the right-hander owns a staggering 5.80 ERA. His peripherals don’t look much better either. He has a 5.34 FIP, a mark well out of line with his career average. Save for a complete game shutout in Boston, Tanaka has looked lost on the mound.

No matter which way you dice it, the Yankees ace has struggled in 2017. He’s pitched below his career norms in almost every category. What explains this ineffectiveness? In order to answer that question, it makes sense to first dive into Tanaka’s performance. The below table documents the right-hander’s splits over the last two seasons.

The contrast in these numbers is striking. Last season, Tanaka pitched his way into the Cy Young discussion. This year, however, opposing batters are squaring him up. He appears especially ineffective to right-handers. They’ve posted a ridiculous .617 slugging percentage off Tanaka. For comparison’s sake, that’s close to Alex Rodriguez’s .300/.392/.623 triple-slash in 2002. Turning batters into peak A-Rod is a suboptimal strategy.

Tanka neutralized right-handed batters last season. How did these numbers spiral out of control in 2017? Sometimes location explains such discrepancies. A look at the charts, however, suggests this isn’t the case. First, here’s his map against right-handers this season.

Compare that to his location in 2016:

Those look fairly similar to me. No areas stand out as notably different. If location doesn’t explain his ineffectiveness, then perhaps pitch selection does. Tanaka has allowed six home runs to right-handed batters this season. Per Baseball Savant, half came on splitters and sinkers. Those are Tanaka’s trademark pitches. If he struggles with them, it makes sense that his results will suffer.

In order for a splitter or a sinker to be successful, the pitch must have a significant vertical drop. Ideally, the batter reads fastball before swinging over a ball that dives out of the strike zone. At his best, we’ve seen Tanaka pull the string on vicious splitters. They were the kind where the bottom drops out, and batters miss the target by a foot or more.

Tanaka hasn’t thrown many of those this season. His repertoire of splitters and sinkers looks short. Many of those pitches appear to stay up in the zone, and as a result, right-handers turn on them. In this case, the numbers confirm the eye test. Tanaka isn’t generating much vertical movement this season.

Last year, Tanaka mustered an enormous drop in his splitter, the best in his big league career. This season, however, he’s generating the lowest vertical movement since coming stateside. It’s clear then that a lack of movement on his diving pitches has resulted in Tanaka’s ineffectiveness. Yet that’s only one piece of the puzzle. The more interesting questions, however, revolve around why these pitches don’t drop.

In order to explain the forces behind Tanaka’s flat splitters and sinkers, it makes sense to look at the pitches in action. We’ll focus on the split-finger fastball since it’s Tanaka’s bread and butter pitch. First, a splitter from earlier this season:

Now compare that to one in 2016.

For the most part, these displays look similar. Tanaka’s mechanics are effectively unchanged. His back leg collapses at about the same time in each segment, and he drives forward with similar intensity. What does look different, however, is his release point. In 2016, the ball leaves Tanaka’s hand at nearly an over-the-shoulder spot. This year, however, his release point hits at a lower arm slot.

This difference isn’t unique to Tanaka’s sinking pitches. He’s pitched with a different release point all season.

Could this explain his ineffectiveness? It’s possible. Batters might have an easier time reading the ball out of his hand at this angle. He could lose deception with a different release point. Or perhaps it’s preventing Tanaka from finishing his pitches. We know that the splitter and sinker aren’t diving out of the zone. He might need a higher release point to more effectively drive the ball down.

Tanaka is a tinkerer on the mound. He frequently makes adjustments and is known to alter his repertoire accordingly. I don’t think we’ve seen the same version of Tanaka twice. He appears to constantly reinvent himself. That leads one to suspect that he can correct this issue. He’s a smart pitcher, one who knows what mistakes he’s making.

Following his difficult outing against the Blue Jays earlier this month, Tanaka weighed in on his struggles to the New York Post. “A lot of my pitches caught the plate too much,” he said, “that is one of the reasons I wasn’t as good as in Boston.’’ He knows that in order to be successful, he has to get his sinking pitches out of the zone. The more he fiddles with his release point, the more likely it is that he’ll find a spot that works.

It’s no exaggeration to suggest that Tanaka is among the most important players on the Yankees’ roster. He’s the staff ace, and he needs to perform up to his expectations if the the club wants to succeed. Tanaka’s been awful for most of the season, especially when it comes to right-handed batters. If he can generate more sink, however, it’s possible to right the ship. Considering it’s a contract year, and the Yankees appear poised to content, it would behoove Tanaka to do so as quickly as possible.