Tanaka Doesn’t Like to Stretch

Masahiro Tanaka decided to create more questions than answers in my life. I just released my first 2018 pERA run and Tanaka’s pitches and control point to a 2.88 ERA but he’s posting one nearly two points higher at 4.95. I dove into his stats hoping to find a simple answer, instead, I found someone struggling out of the stretch while throwing harder. While it explains his struggles, I am not sure any of it matters. At least not yet.

The first item I checked for with ERA and estimators diverge is a high BABIP which was only at .243, about 30 points lower than his career average (.276). Nope, not BABIP.

And then onto his 65% LOB% which is 9% points below his career average and caused by a 1.8 HR/9. Last season, he allowed the exact same rate with a 71.5% LOB%. Over the last two seasons, he seems to be allowing home runs with runners on base. This season he’s allowed 11 home runs total with six coming in the 161 times the bases were empty. When a runner was on, it was five is just 70 batters faced. To look at his struggles anther way, here’s is vsSLG over the a past four seasons.

Tanaka’s vsSLG
Season Bases Empty Runners on
2015 0.431 0.393
2016 0.364 0.390
2017 0.452 0.494
2018 0.367 0.581

The .581 is 165 points above the league average for starters. So I went diving into the data and watched him throw. I conluded, he’s just horrible from the stretch this year. Here a comparison of his windup and stretch from the first inning of his last start.

via Gfycat

via Gfycat

Tanaka’s windup has pauses and he does a good job of hiding the ball. Out of the stretch, he just rushes his throw home with no chance to hide it behind his knee. I went back and watched some pitches out of the stretch from previous seasons and his motion is the same. I was perplexed on what changed.

Finally, I examined his pitches with the bases empty or with runners on. The results were a little striking.

Tanaka’s Pitch Velocities
Fastball Slider Splitter
Season Bases Empty Runners on Diff Bases Empty Runners on Diff Bases Empty Runners on Diff
2016 91.8 92.3 0.5 83.9 84.5 0.6 86.7 87.1 0.4
2017 91.8 92.3 0.5 84.1 84.7 0.6 87.0 87.5 0.5
2018 91.7 92.7 1.0 83.0 83.6 0.6 86.0 86.7 0.6

He’s thrown quite a bit harder out of the stretch but he’s taking it to new highs this season, especially with the fastball. The extra velocity is good and bad.

The extra velocity helps make his fastball and slider harder to hit but the extra zip straightens out his split-finger fastball making it worse.

Tanaka’s Pitch SwStr% Change From Windup to Stretch
Pitch 2016 2017 2018
Fastball 5.4% 6.7% 13.9%
Splitter -3.6% -3.7% -4.2%
Slider 5.9% 6.4% 1.5%

While the pitches from the stretch may have a little swing-and-miss, they lose their movement and are getting crushed when hitters connect.

Finally, Tanaka has not been able to help himself out by. With runners on, he’s striking out fewer batters and walking more compared to any time during his career.

Tanaka’s Plate Discipline Stats with Runners On
Season K% BB% K-BB%
2014 26.5% 4.4% 22.1%
2015 19.7% 8.0% 11.7%
2016 21.0% 5.5% 15.5%
2017 24.1% 6.4% 17.7%
2018 17.1% 8.6% 8.6%

While it wasn’t obvious to me in my limited viewing sample, his ability to control the strikezone with runners on doesn’t exist.

Expect some future studies about pitchers struggling (and thriving) while throwing from the stretch. After taking an initial dive into the subject while working on this article, no single metric stands out. Additionally, I’d like to examine how common are velocity changes depending on if there on runners on or not.

My working theory is that he’s rushing his throws home. This could be to help him control the running game or it’s a quirk he needs to remedy. The problem for his owners, they don’t know when it will be remedied.

Simply, Tanaka is struggling with runners on base but I have no idea if it’s predictive or owners should expect regression. One step forward, two steps back. The story of my life.

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Jeff, one of the authors of the fantasy baseball guide,The Process, writes for RotoGraphs, The Hardball Times, Rotowire, Baseball America, and BaseballHQ. He has been nominated for two SABR Analytics Research Award for Contemporary Analysis and won it in 2013 in tandem with Bill Petti. He has won three FSWA Awards including on for his MASH series. In his first two seasons in Tout Wars, he's won the H2H league and mixed auction league. Follow him on Twitter @jeffwzimmerman.

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Great article. Thanks, Jeff!