Since joining the Yankees in 2014, Masahiro Tanaka has provided a stable presence at the top and middle of their starting rotation. In his six years as a Yankee, Tanaka has averaged 167.2 innings pitched per season, to the tune of a 3.75 ERA (113 ERA+) and a 3.88 FIP. However, it is in the postseason where he truly shines, allowing a stingy 1.76 ERA and 0.783 WHIP over 46.0 innings pitched.
Tanaka’s capacity as a true three-pitch pitcher enables this success. He keeps hitters off balance mixing his fastball, slider, and splitter, whose usage rates have all exceeded twenty percent in each big league season. This unpredictability is enhanced by Tanaka’s willingness to throw all three pitches in any count, more than making up for the lack of velocity on his fastball and the relatively narrow disparity in speed between his hard and breaking/offspeed offerings. Perhaps most impressive is his consistent ability to deliver each pitch in the same arm slot and plane, which when paired with the sharp break on his slider and splitter, makes for a devilish task for opposing batters.
Masahiro Tanaka, Fastball, Slider and Splitter, Overlay. pic.twitter.com/yVhaYjYah5— Rob Friedman (@PitchingNinja) May 24, 2019
Long one of the best pitches in baseball, Tanaka’s splitter became even more devastating after he made the switch from sinker to four-seamer as his primary fastball offering beginning in 2017. Between 2017 and 2018, his splitter produced a paltry .218 xBA, .344 xSLG, and .263 xwOBA. When matched with a 37.3% whiff rate and 26.9% put away rate, Tanaka’s split stood as a borderline unhittable pitch.
This all came to a screeching halt in 2019. After three initially promising starts, by mid-April, Tanaka’s effectiveness with the splitter plummeted. On the season, he was only able to generate an 18.5% whiff rate and 13.6% put away rate. Predictably, his expected stats suffered as a consequence, ballooning to a .291 xBA, .413 xSLG, and .306 xwOBA. Opposing batters found it easier to lay off the once-deceptive pitch, and when they made contact they punished the baseball. So where did it all go wrong?
Tanaka himself has provided a hint as to the suspect in this case. In August of last year, Tanaka told the New York Times that when he gripped the ball “it feels a little bit different.” Indeed, a report by The Athletic confirmed that the seams on the baseballs in 2019 were lower relative to previous years. It’s easy to see how this would have a tremendous impact on a pitcher’s ability to manipulate the baseball. Lowered seams could make it harder to grip the ball, and therefore more difficult to achieve the desired effect. According to Tanaka, that manifested in the splitter in the form of “not giving you the vertical drop.”
An investigation on Brooks Baseball bears this out. Between 2017 and 2018, Tanaka averaged about 30 inches of drop on his splitter including gravity. In 2019, he only managed about 27.8 inches of drop. Splitters that normally would drop out of the zone were staying elevated in 2019, and were getting crushed.
When you pair this with a look at his aiming point, the full picture begins to emerge. From 2017 to 2019, the vertical pitch location of Tanaka’s splitter did not significantly vary. His splitter on average finished between 16 and 17 inches below the center of the zone, or about four to five inches below the zone. However, knowing that he managed more than two inches less drop in 2019, this means Tanaka’s aiming point as the ball left his hand was correspondingly two-plus inches lower than in 2017-2018. A pitch that would initially look like a strike and then dart out of the zone was instead always starting below the zone. Batters found it a much easier task laying off the low splitter, and this is reflected in his depressed whiff and chase percentages.
The numbers on the above chart beginning in August give reason for optimism. Tanaka saw the drop in his splitter steadily increase so that it was achieving the dip one is used to seeing by the end of the season. This coincides with the decision to alter his splitter grip. Tanaka revealed that in his July 31 start against the Diamondbacks, he switched from positioning his index and middle fingers along the seams to positioning them across the seams. This makes sense, given what we know about the lowered seams. Perhaps this new grip allowed him to get better purchase on the baseball and prevent it from slipping.
The results were immediate, with Tanaka seeing an uptick in the number of whiffs against his splitter. Expectedly, the batting average and slugging percentage against his splitter both dropped in the second half of the season. This wave of positive momentum carried him into the playoffs, where he was his usual sparkling best.
Masahiro Tanaka is an integral cog of the Yankees’ starting pitching, providing a different look from the three flamethrowers ahead of him. His guile in the use of three plus-pitches is key in keeping hitters uncomfortable. With James Paxton set to miss at least the first third of the regular season, the Yankees will lean even more heavily on Tanaka to produce on the mound. A large part of his success is owed to his wipeout splitter, and if he truly has found the antidote for the lowered seams, expect Tanaka to solidify the middle of the Yankees’ rotation.