Masahiro Tanaka’s Daylight Problem
Is there anyone having a weirder season than Masahiro Tanaka? Dude is in the top fifteen when it comes to strikeouts minus walks, and yet he’s got an ERA over five. He’s been better recently! And he’s done it by… refusing to throw fastballs. Despite this wrinkle, he’s still giving up nearly two home runs per game. We haven’t even gotten to the weird day/night splits, but they’re part of the story, too. Weird.
Here’s a strange coincidence. On May 22nd, I wrote that — since batters are increasingly hunting fastballs and swinging dead red on every pitch in the era where strikeouts aren’t necessarily penalized — it was time for a pitcher to consider throwing 80% breaking balls. On May 20th, Tanaka started throwing breaking balls more than half the time. He’s thrown more than 60% breaking balls in four games since. He’s getting close.
To some extent, the idea is simple. Balls put in play off of sliders, curves, and cutters aren’t hit as hard. And batters are looking for fastballs. So don’t give them what they want!
| Pitch | BACON | ISOCON | Launch Angle | Exit Velocity |
|---|---|---|---|---|
| 4-Seam | 0.302 | 0.160 | 15.8 | 88.4 |
| Sinkers | 0.319 | 0.153 | 5.8 | 87.7 |
| Cutters | 0.296 | 0.165 | 10.8 | 85.1 |
| Sliders | 0.299 | 0.147 | 11.9 | 85.0 |
| Curves | 0.303 | 0.137 | 8.7 | 85.2 |
| Changeups | 0.283 | 0.164 | 8.2 | 84.7 |
Coming into this season, Tanaka’s best pitches when it came to slugging results in play were his vaunted splitter, his cutter, and his slider. So he lined up well to be our guinea pig. Throw less of the bad stuff and more of the good stuff and the homer problem will go away!
Obviously it didn’t. The pumped up curve and slider are not the problem. He’s given up five homers on the two pitches combined since he started featuring them harder, but the combined .143 isolated slugging percentage is below league average and the best he’s got other than his now show-me four-seamer. The cutter’s .192 ISO allowed in that time frame is not great, but not killer.
The sinker, though. He’s giving up a .373 isolated slugging percentage and seven homers in half the number of pitches as his slider since he stopped throwing sinkers as often. Think of it. He’s thrown as few as three sinkers in a game since, and it’s still getting lit up. His splitter has taken a turn for the worse, too. And it bears out in the movement — his splitter is slower than it’s ever been, and it’s dropping less than it was earlier this season.
Still.. ever since he dropped his arm slot to its lowest point this season, he’s getting the best sink he’s ever gotten on his pitches. Why is he giving up homers on these pitches?
Are his day/night splits related? For his career, Tanaka’s strikeout minus walk rate gets 1% worse during the day, but his isolated slugging percentage allowed goes up from .158 to .195. His results are 15% worse than league average during the day and 9% better than league average at night. This year, it’s even nuttier — he’s 32% better than league average at night, and 159% worse than league average during the day. He’s allowing a .467 ISO during the day.
Does his stuff move less during the day? Not when it comes to drop. His sinker and splitter have almost exactly the same drop in day and night games. Does he leave his sinkers up in day games? No, the difference is half an inch in aggregate. Looking through heat maps just makes you realize how few sinkers he’s throwing these days, and somehow they’re still getting hit hard.
Does the weather affect him? Maybe. Look at this stark difference in launch angle and exit velocity during day and night games this year.
| Launch Angle | Exit Velo | |
|---|---|---|
| Day Games | 17.4 | 90.1 |
| Night Games | 5.6 | 87.5 |
Batters have been putting the ball in the air with authority in day games this year against Tanaka. Let’s return to movement because something has to be happening here. Horizontal movement informs ground ball rate on the sinker, and, lo and behold, Tanaka’s stuff is flatter in the day when it comes to horizontal movement.
| Day | Night | Difference | |
|---|---|---|---|
| Curve | 7.5 | 8.4 | 0.9 |
| Cutter | 4.5 | -0.9 | -5.4 |
| Four-Seam | -6.4 | -8.5 | -2.2 |
| Splitter | -12.5 | -13.3 | -0.8 |
| Sinker | -14.5 | -16.6 | -2.1 |
| Slider | 3.4 | 2.2 | -1.2 |
Remember we were looking for reasons that his cutter, splitter, and sinker would give up more homers during the day. Looks like his sinker and cutter have wide differences in movement in the daylight vs at night. His cutter goes from having cut to… backing up and moving to the arm side.
They why is not obvious. Perhaps it has to do with grip on the ball, though usually warmer weather is more humid, which makes it easier to grip the ball. Perhaps it has something to do with the interaction of his new arm slot, new sink, and less sink during hotter starts.
Let’s return to the overall, unsplit results, then. There’s evidence that his newest mix — light on sinkers and heavy on splitters and sliders — is the best one for him. It’s the best combination of strikeouts and ground balls at least.
| Sinker | Cutter | Slider | Curve | Launch Angle | K% | |
|---|---|---|---|---|---|---|
| 4/2-5/14 | 27% | 11% | 22% | 6% | 8.1 | 17.7% |
| 5/20-6/17 | 24% | 6% | 35% | 6% | 10.6 | 28.3% |
| 6/23-7/28 | 14% | 9% | 33% | 8% | 6.8 | 26.4% |
This seems easier to hold on to. Ever since Tanaka dropped his arm slot, his slider has had above-average whiffs and hasn’t been a problem on balls in play. That’s given him, with his cutter, three breaking balls that he can throw in lieu of his sinker, which is getting throttled. He’s come close to solving that problem by throwing the sinker less and the breaking balls more.
The last bit? The home runs? The day game problem? Turns out his stuff is straighter during the day. The why, though, that remains elusive. Told you it was a little weird.
With a phone full of pictures of pitchers' fingers, strange beers, and his two toddler sons, Eno Sarris can be found at the ballpark or a brewery most days. Read him here, writing about the A's or Giants at The Athletic, or about beer at October. Follow him on Twitter @enosarris if you can handle the sandwiches and inanity.
He’s secretly a vampire. That’s why.
Great, now I can’t stop imagining Tanaka as an anime vampire.
Count Tanakula
Is it a coincidence that Tanaka is starting a day game today???
The weather thing would be easy to check–just look at weather at start time for all outdoor games. But it’s not like everyone else is having the same problem, so unless he sweats more on his hand than your average MLB player it’s hard to see how it would matter.
I wonder if it’s simpler than that. It’s something that only affects Tanaka, right? So something like eyesight or taking naps on game day…
Seems worth noting that he’s only pitched 5 day games this year, vs. 16 night games. And 4 of his day games have been on the road.
It’s not just this year, though, it’s been a problem in his career, it’s just worse this year.
Oh, sure, I’m not saying the low number of day games invalidates the analysis, just worth noting re: this year’s spike.
There seem to be lots of players, pitchers and hitters, with day night splits, and for different reasons. Day games are morning games for baseball players. Doc Gooden was terrible by day, but there were complicating factors there.
Note that 1 of his day starts was opening day indoors in Tampa Bay. That’s a lot different than an outdoor day game.
I would also note that we are talking about only 6 day games. Could just be small sample size.
It’s been a problem his whole career, though, and is just worse this year. Of his 14 night games, only two had as bad launch angles as his best day game, which was the Tampa one (11 degrees). It’s stark
Its probably a SSS thing. A number of day starts came in cooler weather in April and May and most of them when he was going poorly.
However, maybe he has been hitting the bottle and is not 100% earlier in the day. Or maybe he has a sleeping problem and needs afternoon naps. Sheer speculation
“SSS” doesn’t really explain the contrast in “stuff” though… I wonder if his day game in TB (indoors) contrasts with the stuff/movement in the other day games? Maybe isolate this to an outdoor, daytime issue, which would possibly inform if it is weather-related?
Tanaka is bad in daylight. Tanaka is good with an extra day of rest. Why not skip him in day games? A parent with two children where one is more talented but also more contextually driven, you favor him and sacrifice the dud. It will be better for both of them, because the unlovable loser kid will get tougher through adversity.
Parenting 101, everyone agrees.
14.5 versus 16.6 inches? Let’s see those sinkers as day/night clusters. I’m going to bet the clusters overlap a ton.
The day/night possibility is interesting but I’d be more into validating the concept before using it to explain Tanaka. Do other pitchers show this, is it robust, is it not driven by other factors like park measurements effects.
i wonder if it could possibly be the black tarp the Yankees and other teams have in CF for the batters, maybe it’s easier for them to see spin rate / pickup pitches quicker in day games because the contrast of the light is better than in the evening / night? Like could Tanaka possibly be dropping his arm slot correlate to his entire arm and ball being in the batter eye box tarp thing?