If I asked you which one of Masahiro Tanaka’s pitches were most important, you would probably say his splitter, since it’s one of the best in baseball. Perhaps some of you would mention his slider, which would also be fair. Since 2014, Tanaka’s first season with the Yankees, both of these have been above average pitches for him in each season. Fangraphs has a nice, tidy chart which tells us how many “runs above average” each pitch in a pitcher’s repertoire is. Here is the data on Tanaka from 2014-2017:
From left to right, the chart tells us about Tanaka’s 5 primary pitches: four seam fastball, slider, splitter, sinker, and curveball. As we’ve already discussed, his splitter and slider have been fantastic in each season. His curveball is about average; he rarely throws it, and uses the pitch just to steal a strike on occasion. This brings me to my point: Tanaka’s most important pitch in 2018 will be his sinker. He throws fewer four seam fastballs then he used to, and needs to utilize his sinker so hitters can’t just sit on his splitter or slider. The problem is his sinker was inconsistent at best last year, and yielded a ton of extra base hits. Tanaka also gave up a whopping 21.2% home runs per fly ball last year, which was the worst in the league by a wide margin. This was the biggest change between his 2016 season (3.07ERA, 3.51FIP, 4.6WAR) and last year (4.74ERA, 4.34FIP, 2.7WAR). Let’s compare his pitch outcome data from 2016 and 2017 via brooksbaseball.net:
Focus on Tanaka’s sinker here. Notice the stark difference in the 2 years: batters slugged only .359 against Tanaka’s sinker in 2016. In 2017, that number ballooned to .634(!). To put this into terms you can talk to your grandpa about: that’s basically the difference between Ronald Torreyes (sorry Toe) and Aaron Judge. Since his breaking pitches are his bread and butter, this makes Masahiro’s sinker extremely important. He needs this variance in velocity to keep hitters off balance.
Let’s dig deeper into why Tanaka’s sinker wasn’t as effective in 2017.
You can notice the stark change in movement in Tanaka’s sinker between the 2 seasons. In 2016, he averaged 5.61 inches in vertical movement, in 2017: only 4.34 inches. Tanaka lost over an inch in vertical movement between seasons, and while these numbers typically fluctuate from start to start, that’s a large variation between years.
There is a good chance that Masahiro Tanaka will rebound this season. He will always give up the occasional homerun; that’s just the danger you live in when you have a slider/splitter heavy arsenal. I do think there is a decent chance that he will cut down his home run rate from the gaudy 21.2% we saw last year. A good start would be finding that extra vertical movement in his sinker to help set up his stellar breaking pitches.