Masahiro Tanaka's secret weapon

Mashahiro Tanaka is every bit as good as advertised. The new Yankees ace is putting up video game numbers through the first eight starts in New York. He leads baseball with an eye-popping strikeout-to-walk ratio, counting 66 strikeouts against just seven walks. 

Tanaka’s splitter gets most of the attention as it is nearly unhittable, the kind of pitch that gives batters fits. It might be the single most devastating pitch in the game right now. Batters wave over it as it dives out of the strike zone, coaxing more swings and misses and sealing more strikeouts than any of his myriad offerings (Tanaka also throws a curve, at least two fastballs, a slider and a rare changeup.)

While the splitter gets the acclaim and keeps hitters up at night, it is his slider that does a lot of the heavy lifting. It’s not as spectacular a pitch as the split but Tanaka throws it 30% of the time and, despite its pedestrian appearances, it is very effective.

How it’s used

Most pitchers use their slider as a weapon similar to the way Tanaka uses his splitter - they throw it with two strikes, looking for a swing and miss. Often thrown out of the strike zone, it is designed to look like a strike as it leaves the pitcher’s hand but designed to avoid harm and the barrel of the bat.

Good sliders are hailed for their “depth” and movement - which is to say they move both laterally as well as down in the zone. More movement, fewer hard hit balls. When a slider isn’t well executed, it is easy to hit a long way. These sliders are best often called “spinners” or “cement mixers” and often end up in the seats.

Tanaka uses his slider differently so he throws it different. Rather than the sweeping break of Tim Lincecum’s or Felix Hernandez’s slider, Tanaka’s pitch is both flatter and “shorter”, meaning it breaks less.

Tanaka controls the movement of this pitch because, for him, it is a pitch he often throws for strikes. In fact, one of the most most common places for him to place his slider is right down the center of the plate.

The below diagram shows a zone-by-zone breakdown of every slider Tanaka’s thrown this year from the catcher’s perspective. The hot zone in the bottom corner is typical slider placement against right handed batters. Against lefties, Tanaka throws it on the outside corner, “back dooring” the pitch for a called strike. But it is the slider right down the middle that really stands out.

Why it works

Of the four pitches Tanaka throws regularly (four seam, two seam, slider, and splitter), batters swing at his slider the least. They put it in play the least. He throws it for strikes the most - in any count, against righties or lefties. Batters can’t key on it because they have so many other weapons to key on.

It is testament to the quality of his other pitches that he “gets away” with throwing an altogether “middling” pitch for strikes so consistently. But the pitch, while it doesn’t spawn oohs and ahs and heavily-shared GIFs, works because of what it isn’t, not what it is.

Last night, Tanaka threw one of his patented “get me over” sliders to David Wright, the best hitter on the Mets by a considerable margin. After starting him with his big curveball (one of Tanaka’s other specialties, the first pitch slow curve), the Japanese right-hander cut this tiny slider over the middle of the plate. And Wright watched it go by.

This is a typical of the way Tanaka throws this pitch - it’s a bridge to his splitter and counterbalance against his fastball. Hitters aren’t able to identify his best pitch, but if they see “not fastball” in the lower half of the strike zone, they’re likely to lay off as the fear of the splitter diving under the strike zone (or their bat) is too great.

Versatility is key

Just to make matters more confounding for hitters, every so often Tanaka will break down and throw a more “traditional” slider with two strikes for a swing-and-miss. After victimizing David Wright with the 0-1 slider seen above, Tanaka got him fishing with one down and away in the eighth inning.

Earlier in the game, Tanaka dispensed with the opposing pitcher, Rafael Montero with a nasty slider after throwing two straight fastballs. Quick and painless, not a pitch wasted.

And for good measure, in the ninth inning and driving for the complete game shutout, Tanaka flipped the script against Ruben Tejada, throwing a slider through the front door, a pitch that started at his hip and ended up catching the inside corner.

The ongoing evolution of MasahiroTanaka

Tanaka is a great pitcher for a variety of reasons. He throws strikes with all his pitches and earns swing and misses with his breaking balls. He is able to pump his fastball up to 95 mph when required and his deadly splitter keeps hitters honest in just about every count.

It is still very early. One day, the entire American League could rise up and stop swinging at his splitter altogether. Unlikely as that might be, Tanaka is the kind of pitcher willing (and able) to work around a day when he lacks his best stuff. As observed during his first ever big league start, he is willing to stick with a pitch when it doesn’t feel great - an admirable trait indeed.

He’s an ace, in other words. The marriage of stuff and wisdom that teams happily fork over $155 million dollars given even a half a chance. His highlight reel split fingered fastball might get all the accolades but his secondary stuff, his brutally effective slider among them, set him apart.