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Hisashi Iwakuma will never be great again

The Mariners' No. 2 starter has hit his ceiling. Injury and decline is the new normal.

MLB: Toronto Blue Jays at Seattle Mariners Joe Nicholson-USA TODAY Sports

Remember the days when we couldn’t wait to get Hisashi Iwakuma over to the Majors? And remember when he did finally get here, and it was cool as hell? Another junkballer from Japan, laying in splitters and making hitters eat their lunch. 2013 was a special year, one that we didn’t treat with the respect it deserved.

Now we live in 2017, and Iwakuma’s 21923 inning, 79 DRA-, 6.6-WARP campaign is but a distant memory. Iwakuma chewed up some innings in 2016, but he just missed crossing the 200-frames threshold. His performance collapsed, and while being a league-average starter isn’t exactly something to sniff at, Iwakuma still appeared a shell of his former self.

Things don’t seem likely to get any better, either. Iwakuma is about to enter his age-36 season. He has a history of injury, and the Dodgers were so scared of his health that they backed out of a multi-year deal with Iwakuma after they administered a physical.

So, what went wrong for Iwakuma last year? Is there anything he can address to at least stave off Father Time, or is it all just hopeless?

No one would ever accuse Iwakuma of being a power pitcher, given his fastball velocity and lack of dominating strikeout totals. Be that as it may, Iwakuma still managed to put up above-average strikeout rates in this three previous seasons, and thanks to his superlative control, his 17.5 percent strikeout-minus-walk rate was tied for 18th among the 122 pitchers who tossed at least 300 innings from 2013-2015.

All of those numbers trended in the wrong direction last year. Iwakuma posted a significantly below-average strikeout rate for the first time in his major-league career. Perhaps more worrying, he seemed to lose the strike zone a bit, posting his highest walk rate since his rookie season.

It appears that hitters stopped offering at his breaking pitches. Iwakuma’s O-Swing rate dropped more than seven percentage points from 2015 to 2016. As a result, Iwakuma began throwing more pitches in the zone, as his Zone rate jumped to 52 percent, well above league-average. The scary part is that hitters continued to make high amounts of contact on pitches in the zone, and with more pitches to hit, Iwakuma got lit up.

Iwakuma loves his splitter. It’s his primary out pitch, and he consistently throws it more than 30 percent of the time in two-strike counts. Of those two-strike splitters, 38.3 percent of them ended in a strikeout or ground ball in 2015. Last year, those two-strike splitters became a strikeout or a ground ball only 33.7 percent of the time. Small-sample fluke? Maybe. But it’s clear that the effectiveness of the pitch may have been on the wane.

The contact on that splitter was of less desirable quality, too. Iwakuma gave up an 89.3-mph average exit velocity on his splitter last season, higher than league average. In 2015, he gave up an 84.9-mph exit velo. The league average was 87.4 mph. Iwakuma’s average launch angle on the splitter jumped more than four degrees, too. The pitch was getting hit harder and higher last year, precisely what you don’t want to have happen on an offering that lives in the bottom of the zone.

That launch angle issue is especially relevant: Iwakuma just stopped getting ground balls last year. His ground ball rate cratered by nearly 10 percentage points from 2015 to 2016, dropping to a career-low 40.8 percent. His average launch angle jumped nearly four degrees. The Mariners outfield was quite bad last year, so more fly balls and line drives were the last thing Iwakuma needed. A control-and-finesse guy like him has to keep the ball on the ground, and he failed at that.

So what is Iwakuma supposed to do? It’s not at all clear. His velocity will continue to drop. Without expert control, an 89-mph fastball will be eaten alive. If he can no longer get ground balls, then his contact profile will also continue to suffer. Moreover, he will be 36. He dealt with nagging injuries throughout 2014 and 2015, and at least one organization believes that something more serious could be lurking underneath the surface.

Could Iwakuma have been dealing with some latent injury last year? It wouldn’t surprise me. He and the Mariners won’t say, and no sources have suggested it, either. All we are left with is the promise of a once-great career that is about to drift off into the twilight, on a team that could desperately use his greatness again.