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Don’t Fall Behind Hisashi Iwakuma

There aren’t many reasons to watch the Seattle Mariners. For several years now there was a singular reason to do so and it had something to do with a guy who goes by “King.” But in 2013, there’s an encore for every Felix Hernandez gem and his name is Hisashi Iwakuma.

Seattle is the kind of media market that ensures players fly under the radar (see Martinez, Edgar). So there are probably plenty of you that look up from your spreadsheets and see a 7-1 record with a 1.79 ERA and 0.82 WHIP and wonder how you could have completely forgotten about this guy.

Nevertheless, here we are in mid June and Iwakuma has the second best ERA in baseball (among qualified starters) and damn near the same strikeout rate as Clayton Kershaw. While it seems extremely unlikely that Iwakuma can keep this up, the question on my mind is whether he can replicate any sort of approximation of his first 14 starts.

There are two quick things to keep tucked away in the back of your pretty little heads when pondering Iwakuma’s future. One, he’s had a series of shoulder issues in his career, although he’s been relatively healthy going on two seasons now. This is ostensibly why the club used him out of the pen to start 2012 and also why he’s only averaging 93 pitches per start in 2013. Most pitchers are ticking time bombs, but in Iwakuma there’s definitely increased risk.

Second, this 2013 performance isn’t necessarily out of the blue. His 2012 totals were dragged down by a 4.75 ERA and 1.42 WHIP over 30 innings in relief while as a starter, he posted a 2.65 ERA and 1.23 WHIP. Not otherworldly results as a starter, but his xFIP as a starter in 2012 was 3.61 and it’s 3.13 this season — so at least it’s in the vicinity of the same ballpark. Maybe outside in the beer garden.

And lest you’ve forgotten your history, there was a reason the Oakland Athletics bid $13 million bucks to just have the right to negotiate with him back in 2010. His record in Japan wasn’t Darvishian but over just about 1000 innings pitched, Iwakuma had a career 3.14 ERA and 1.19 WHIP, striking out 747 batters over that stretch.

But on to the how.

The best way I can probably describe it isn’t going to be terribly satisfying to many of you — but Iwakuma just appears to be a really smart pitcher. He knows his strengths and weaknesses and seems to just maximize situations in which he can pitch to his strength.

Here’s Iwakuma’s repertoire ( yeah, I know that doesn’t add up to 100%, he also throws a curve sparingly):

Fourseam 30%
Slider 19%
Splitter 21%
Sinker 23%

According to pitch values, each of these have been well above league average with his splitter being among the very best in the league (and, in fact, better than Yu Darvish). But yeah, it’s probably premature to be citing pitch values this early in the season.

Iwakuma doesn’t have an overpowering fastball. It sits right about 89-90 mph. But he uses it frequently as his first pitch in an attempt to get ahead in the count to set up the splitter. The fastball is his first pitch in almost 50% of at bats to left handed and right handed batters alike. If it’s not his fastball, he uses the sinker 30% of the time to lefties and his slider 30% of the time to righties. It’s almost never anything else.

When he’s behind in the count though, Iwakuma doesn’t just give in. Versus RHB, he’ll still go sinker/slider almost 60% of the time. Versus LHB, he goes to the sinker 50% of the time. Why does this matter? Well, because his fastball ain’t that great — and somehow, Iwakuma manages to induce batters into swinging at his junk (settle down, Beavis).

In all three-ball counts this season, with any combination of strikes, here’s the number of times he’s thrown his splitter and his sinker for strikes, and the corresponding percentage of swings:


For a guy with a 3.9% walk rate, Iwakuma isn’t looking to give up much in the way of free passes. Yet he’s very rarely throwing the ball in the strike zone in three ball counts while still inducing batters to swing at the crap almost three quarters of the time. Yahtzee.

With a little help from our friends at BrooksBaseball.net, we can see the percentages of swings in and out of the zone:


So he’s generating almost as many swings outside of the zone (low and away to lefties) as he does right down the middle. What’s perhaps more important are the swings and misses:


When Iwakuma is ahead in the count, he’s been practically unhittable. When ahead, he’s held opposing batters to a .152/.150/.276 slash line. He’s walked exactly zero batters and struck out almost 40% of them.

Obligatory gif’s:




You’re all sharp enough to look at the ERA predictors and surmise that he’s not likely to continue to post a sub-2.00 ERA, but the fact is that if Iwakuma can stick with the same recipe every fifth day, he’s probably going to be very effective. Because there’s not a lot of guesswork going on about what he’s going to throw in the count — hitters ought to know this by now and adjusted — and it’s still not enough to square up many balls. Depending on the return, you could certainly venture to sell high, but if I’m an Iwakuma owner, I’d cling to him.