How many times have we seen hitters wave helplessly against Masahiro Tanaka’s splitter over the years? Too many times to count. This season has been a different story, though. For whatever reason, Tanaka has struggled to hone his splitter. He’s been frank about its lack of effectiveness, though it hasn’t held him back. Tanaka has his best ERA and FIP since 2016 in spite of his splitter.
Tanaka’s struggle to get a feel for the split has resulted in batters making much more contact against the pitch. Opponents are whiffing merely 18 percent of the time against it, whereas they swung and missed almost twice as often last year. Compounding this issue is that hitters have a .389 wOBA against it after a paltry .252 mark last season. In short, more contact and better results against have forced Tanaka to shy away from his trademark offering.
One problem has been his command of the pitch. When he’s at his best, the righty buries his split-finger down and out of the zone and often in the dirt. This season, he’s located it up a bit more often.
It’s not a stark difference, but (on the right) last year’s darkest red area covers a portion below the strikezone. That’s not the case thus far this year (on the left). Obviously, it’s a lot harder to hit a splitter diving below the zone.
Even though it appears that Tanaka’s lost some precision with the split, it could also be a case of reduced movement. The 30 year-old’s splitter is dropping three fewer inches compared to last season. Perhaps because he’s accustomed to additional drop, he’s having a difficult time adjusting his target.
But why has he lost movement? We’re accustomed to pitchers losing velocity as they age, but not necessarily break.
One thing that jumps out is his spin rate. Last year, Tanaka’s splitter had a 1,468 RPM. This season, it’s up to 1,541. Splitters fall off the table like they do because of their low spin rates — the grip deep between the index and middle fingers prevents the high spin you’d typically see from a fastball. Further, the low backspin makes it easier for gravity to work its magic. Since Tanaka’s spin rate is up, it’s not a surprise that his split is dipping less.
I was also curious to see if release point was a factor. That doesn’t seem to be the case, though. Both his vertical and horizontal release points are virtually unchanged compared to prior years. That’s not surprising given Tanaka’s smooth motion to the plate. However, one thing that did catch my eye was the spin axis on his splitter, which ostensibly relates to his release and mechanics.
The left-most purple dot is 2019, in which he has an average axis of 248 degrees. I’m no expert on this — read Alan Nathan if you’re curious — but what we can glean from his research is that Tanaka’s spin axis on the pitch in 2019 is less conducive to vertical drop than prior years.
One would think that spin axis is derived from release point, but I’ve already pointed out that Tanaka’s release is largely unchanged compared to last season despite a different spin axis. For completeness sake, I decided to arbitrarily take a look at some splitters he’s thrown over the past two seasons to see if I could notice anything.
Maybe I’m grasping at straws, but it kind of seems like Tanaka was more on top of his split last season? It sort of seems like the angle of his arm and wrist is a tad more upright. Again, this is probably a reach. It’s also a sample of two pitches out of hundreds of splitters, so take it with a heaping amount of salt.
It’s not easy to explain, but it’s pretty clear that Tanaka’s depleted vertical movement has hurt his patented splitter this season. Interestingly enough, the movement on his splitter has never been anything special according to new Statcast metrics. Still, there’s no question that drop is integral to the pitch’s success.
Fortunately, Tanaka has been able to ride his slider and four-seamer to a good start in 2019. His 2.94 ERA entering tonight’s game is his best since his rookie campaign. It’s not like he’s done it with smoke and mirrors, either. Yes, his 3.62 FIP is higher than his ERA, but that’s still a very good mark in its own right. Nonetheless, it’s reasonable to be concerned about sustained success without what historically has been his go-to pitch. Hopefully, tonight is the night we get to see his vintage splitter back in action.