It was just before Christmas w 2017 that news broke of the Diamondbacks signing Japanese relief pitcher, Yoshihisa Hirano, to a two-year, $6 million deal. At the time, he was closer in the NPB for the Orix Buffaloes, having saved 156 games for them since making his debut as a 22-year-old in 2006. He joined closer Brad Boxberger as off-season acquisitions last winter, intended to strengthen the back of the Arizona bullpen, and build on the wild-card success of 2017. While things overall did not work out quite as the team hoped in 2018, little if any of the blame for that should go to Hirano, who delivered one of the best rookie seasons by a reliever in franchise history.
Unlike most signings, his official introduction didn’t occur for a couple of months, just as pitchers and catchers were arriving at Salt River. He picked #66, the same number he wore in Japan, but it wasn’t his first choice: “I was hoping to get #16 but Shohei Ohtani already had that number.” The team went into spring without a defined closer, and Hirano had a bit of a bumpy ride, allowing a trio of home-runs in his nine innings of pre-season work, though also had an excellent K:BB ratio of 10:0. It was a time of adjustment, Yoshihisa saying, “In Japan there is a lot more practice, a lot more going into the bullpens, and then you go into the games. Here, there’s not much practice, but you’re preparing with being in the game.”
He experimented with a slider and was also having to come to terms with the slightly different feel of the baseball, “I throw the ball every day, but it still feels slippery. It does run more, but I’m not in love with it yet. I still have to consider (adjustments) a little more carefully.” Still, Hirano was impressing his team-mates and manager Torey Lovullo, who quickly noticed the quality of Hirano’s splitter, a pitch which would be key to his success last year. “It’s hard to gauge until you have a hitter up there, [but] it looked like he was able to throw it, bury it -- possibly at two-strike location, and also throw it up there for a strike.”
Hirano didn’t have to wait long for his MLB debut. He came into the seventh inning on Opening Day, faced two batters and got Mike Tauchman to go down swinging, for his first out in the majors. His opening month had other milestones:. Hirano allowed his first run and home-run on April 3, Logan Forsythe of the Dodgers taking him deep. But on the 27th, he struck out the side against the Nationals, fanning Matt Wieters, Andrew Stevenson and Wilmer Difo on 16 pitches. Though it wasn’t a rigid position, Yoshihisa settled into a seventh inning role for the D-backs, especially when the team had the lead: 32 of his his 75 appearances came with Arizona tied or ahead in the 7th.
Scoreless streaks for Arizona
On May 6 against the Astros, Hirano retired both batters faced. This was of little note at the time, but began a franchise-record streak. Yoshi did not allow a run there, or his next 25 consecutive appearances, breaking the previous best of 24 scoreless games in a row (set by J.J. Putz in 2012 and Brandon Lyon in 2008). The table above lists the ten longest such streaks by appearances. Hirano’s run finally ended on July 4 against the Cardinals, but what’s especially impressive is how self-reliant he was. Of the 26 games - one shy of Koji Uehara for the MLB record by a Japanese-born pitcher - all but three ended with Yoshi closing out the inning, and only one of the 16 runners he inherited came around to score.
Unfortunately, injury robbed us of the chance to see a potential Hirano vs. Ohtani match-up when we faced the Angels [the track-record in Japan strongly favored us: their 15 PA against each other resulted in one infield single and seven K’s]. In June, Fangraphs looked at Hirano’s success and concluded, “The key is the interaction between the fastball and forkball.” While the pitches come out of his hand at nearly the same spot, the difference in their vertical movement is among the largest recorded in the PITCHf/x era. “When a batter sees a pitch coming out of Hirano’s hand, there’s a very good chance that, even if he just slightly misreads the pitch, he will be swinging clean through a splitter.”
As the bullpen imploded in the second half, Hirano stayed strong. Across August and September, Arizona relievers had a 4.63 ERA; Hirano’s was 2.70. With Brad Boxberger and Archie Bradley in particular turning into human gasoline cans wearing Sedona Red jerseys, Lovullo turned to Hirano, who snagged his first major-league save on September 11 (above). He was rewarded with a beer shower from his team-mates, despite his efforts to avoid it: “I tried to go under the radar. I tried to tell them it was the second save.” Of course, the next day, Yoshi picked up his first blown save, but rebounded to close successfully two more times before season’s end, and will be in the mix for the closer’s position again this spring.
As a result Hrano finished the year with three saves and 32 holds, the final one of the latter coming on September 7. If he hadn’t been moved into the closer’s role, he’d likely have broken the major-league rookie record of 34 set by the Padres’ Akinori Otsuki in 2004. But it was still a remarkable season, the greatest in a very long time from any rookie reliever for the Diamondbacks. He certainly deserved to become the first Diamondback mentioned on a NL Rookie of the Year ballot since Ender Inciarte in 2014. By ERA+, here are the ten best such pitchers, with a minimum of 50 innings thrown.
D-backs best rookie relievers
By this stat, Hirano had the best season Arizona has seen in fifteen years, since the 1-2 punch of rookie relievers Jose Valverde and Oscar Villarreal in 2003. Hirano proved to be a real steal on the free-agent market at a cost of $3 million, and at the same price next season, should be equally good value. It might be worth the team looking at an extension - though, as always, a tentacle of reliever volatility languidly breaks the surface at the thought. Hirano may also want to test the free-agent market next winter, especially if he proves his credentials further with a good sophomore season. But, for now, I look forward to seeing many more opposing batters, waving over the top of the Yoshi splitter in 2019.