The Diamondbacks want to build a stronger bullpen, but they say they don’t have much money to spend. As such, instead of talking to Wade Davis or Greg Holland, the club added Brad Boxberger. And now, the club has also added 33-year-old Japanese closer Yoshihisa Hirano, the terms set at two years and $6 million. That’s a little steeper than the two years and $4 million given by the Rangers to Chris Martin, who’s also coming over from Japan. Martin is younger and has been better more recently, but Hirano is more decorated.

Having spent his whole career with the Orix Buffaloes, Hirano has 156 saves to his name. He converted to relief full-time in 2010, and he became a closer full-time in 2013. It’s possible he could close for Arizona. It’s possible Boxberger could close. It’s possible Archie Bradley could close. Maybe all of them will close! I don’t know how it’ll work out, and the Diamondbacks themselves probably don’t know how it’ll work out, but Hirano will get important innings regardless. What does the righty have to offer? It just so happens he faced Nolan Arenado in the most recent WBC. Hirano threw three pitches and got a strikeout. The at-bat opened with a slider:

Then there was a splitter:

Then there was a fastball:

That’s Hirano. Get-me-over breaking ball, mid-80s splitter, low-90s fastball. The slider, he doesn’t throw very much. The splitter is his signature. Or, if you prefer, forkball. I’m not going to pretend to be able to tell them apart. Effectively, there’s no difference. Last year, in Japan, Hirano threw the highest rate of splitters out of all pitchers. We’re talking a little more than two-fifths of his pitches.

Hirano has dominance in his history. Even last year, he had a sub-3 ERA, which followed a year with a sub-2 ERA. But Hirano might’ve been at his best in 2013. You can’t look at his numbers without noticing the following:

Hirano’s strikeout rate has plummeted, which is never a good thing for a pitcher. It’s not what any front office would want to see. On the more encouraging side, though, Hirano hasn’t lost any zip. There exists pitch-tracking data in Japan for the past four years, and Hirano’s fastball and splitter have maintained basically the same velocities. He’s throwing the same pitches he used to. So he could get back to his old level of performance. And there exists a belief he could benefit from the American baseball.

Koji Uehara would be an easy comparison here, and his strikeout rate got better after coming to the States. Masahiro Tanaka and Hisashi Iwakuma also generated strikeout-rate upticks. And I might as well note that, while Seung Hwan Oh doesn’t lean on a splitter, he had a fantastic rookie season in the majors. His last year in Japan, Oh had a K-BB% of 17%. His first year in the majors, it was 27%. Now, Oh also had a much rougher sophomore campaign, but when he signed with the Cardinals, he, too, looked like he could be declining. Instead, he was initially terrific. The Diamondbacks are making a modest bet on Hirano’s stuff staying the same, and his splitter playing up.

Uehara has had an outstanding major-league career, throwing fastballs and splitters with a little less zip. He also, however, appears to command the ball better than Hirano does. Edward Mujica would be a lesser potential outcome. Even he had his uses. Hirano doesn’t seem to be at his peak, and the Diamondbacks won’t look for him to be their savior. But if Hirano likes the ball, there’s a chance he could be a major first-half surprise. The fastball/splitter combination has been proven to work, provided they’re thrown right. Hirano hasn’t lost his arm strength.