Hisashi Iwakuma Persists Under the Radar

As good as he has been as General Manager of the Oakland Athletics, one wonders if Billy Beane would like a taksies-backsies on Hisashi Iwakuma.

It might be hard to remember that Iwakuma was originally posted all the way back in 2010 when they were still making cars called “Pontiac” and “Saturn”. Oakland won the rights to negotiate with Iwakuma, but recognizing he was a year away from free agency, they may never have been all that serious about securing his services at the asking price of his agent, which was reportedly a little ridiculous. So it goes.

In 2012, Iwakuma signed with the Seattle Mariners who promptly threw him into mop-up duty in the bullpen where it appeared Iwakuma was going to be a major bust. Iwakuma posted a 4.75 ERA, 1.42 WHIP, almost a 12% walk rate, and just an 18% strikeout rate until the opportunity arose for him to get a shot at the rotation. And since that time, he’s been one of the better starters in baseball. Believe it.

For the remainder of 2012, Iwakuma pitched to a 2.65 ERA, holding opponents to a .246/.304/.386 slash line, increasing his strikeout rate to 20% and reducing his walk rate to 7%. Since then, he’s only gotten better. In fact, as a starting pitcher in the major leagues, in just under 500 innings, Iwakuma has a career 2.97 ERA, 21% strikeout rate, 4.6% walk rate and 1.07 WHIP. He’s held opponents to a stingy .233/.271/.375 slash line. Over the past two seasons combined, Iwakuma has a 1.03 WHIP, good for 5th lowest in baseball, and ahead of Adam Wainwright, Jordan Zimmerman, Max Scherzer, and Madison Bumgarner.

As you probably know, Iwakuma isn’t a hard thrower. He rarely tops 90 miles per hour. What he does have is a four-pitch arsenal that he uses almost equally, and he’ll throw in a 70 mph curveball once a game to keep you honest. As far as pitch values are concerned, his two best pitches are his sinker and his split finger fastball. His sinker looks an awful lot like his fastball, and he typically uses that when he’s pitching to contact — he generates just about an 8% whiff per swing rate, and almost a 53% ground ball rate on the pitch. The splitter meanwhile generates a 28% whiff per swing rate and just a .192 opponent batting average.

A red flag I’ve been reading about are his 2014 splits and that some of his pitches were “flat” in the second half, leading to better contact. Indeed, Iwakuma had a 2.98 ERA in the first half and a 4.15 in the second half, so he quite obviously gave up more runs. He also gave up quite a few doubles and his walk rate SKYROCKETED from 2.2% to 3.9% (yes, that’s sarcasm). But his FIP splits were 3.20 to 3.30, respectively, his strand rate went from 79% to 68%, and his first half to second half slash line allowed went from .245/.261/.366 to .242/.276/.382. Nothing to get alarmed about.

If you want to look at his first half and second half repertoire in terms of usage, velocity, and movement, there’s really not much to get worked up about here either. Here’s his first half (from Brooks Baseball):

1st Half	Freq	Velo (mph)	pfx HMov (in.)	pfx VMov (in.)	H. Rel (ft.)	V. Rel (ft.)
Fourseam	10.66%	90.06	-7.09	8.21	-2.88	5.42
Sinker	37.34%	89.23	-9.69	4.3	-2.9	5.41
Slider	21.13%	81.09	3.76	1.08	-2.78	5.44
Curve	3.73%	73.19	9.23	-4.23	-2.54	5.59
Cutter	1.18%	87.88	-0.51	6.78	-2.96	5.36
Split	25.59%	85.26	-8.41	0.86	-2.81	5.52

And second half:

2nd Half	Freq	Velo (mph)	pfx HMov (in.)	pfx VMov (in.)	H. Rel (ft.)	V. Rel (ft.)
Fourseam	16.08%	90.32	-6.96	8.71	-2.87	5.62
Sinker	33.15%	89.28	-9.53	4.7	-2.92	5.63
Slider	18.05%	81.02	3.91	1.2	-2.78	5.66
Curve	2.75%	73.55	8.84	-4.51	-2.58	5.8
Cutter	1.34%	87.11	0.49	6.07	-2.93	5.57
Split	28.63%	84.82	-8.31	1.16	-2.81	5.74

His velocity was consistent, so nothing screams injury. His pitch usage was a little more heavy on the fourseam fastball side in lieu of a few sinkers, but nothing huge. And his movement on his sinker, slider, and splitter all look pretty darn consistent to me, so I’m not sure where the “flatness” of his pitches may have come from. Perhaps observers of the ERA.

In sum, I’d say it’s all systems go with Iwakuma. While injury is always a bit of a specter with ‘Kuma given his shoulder issues in Japan, we know that pitchers are simply an injury prone bunch so there’s risk across the board. What he’s shown is pretty great durability, an awfully attractive ERA and WHIP with an ability to pull down a goodly number of strikeouts. With the Mariners projected to actually be decent this season, it’s not out of the realm of possibility he sees an uptick in the fickle win category in 2015 as well.