Once an afterthought, Diamondbacks' Joe Mantiply has been one of baseball's best relievers

Back on Opening Day, Joe Mantiply fired a 3-2 sinker to his second batter of the season — the Padres’ Jurickson Profar. It missed the plate by a fraction of an inch inside and Mantiply stared, hands on his knees, as Profar trotted to first base with a free pass.

It was also the last time Mantiply issued a walk.

Since then, the 31-year-old left-hander has faced 73 batters. Sixteen have reached via base hit. The other 57 have promptly been retired.

“I think I've been executing pretty well,” Mantiply said, underplaying his own accomplishments. Among relievers with 20 innings pitched, he has the National League’s lowest walk rate and, not coincidentally, its lowest ERA at 0.45.

That ability to avoid walking batters is what stood out to the Diamondbacks when they signed Mantiply as a minor league free agent in January 2020, according to assistant pitching coach Dan Carlson, who was then the club’s minor league pitching coordinator. Mantiply had struggled in limited big league experience with the Tigers and Yankees, but he walked just four batters in 38 1/3 Triple-A innings in 2019.

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His low walk rate and high in-zone percentage inspired the Diamondbacks’ analytics staff to take a closer look at him. His film revealed sound mechanics, even in the wake of Tommy John surgery two years prior, giving the Diamondbacks hope that he could make the transformation from a control pitcher to a command pitcher.

While those terms might sound synonymous, the difference is significant at the major league level. A control pitcher can keep his pitches in the strike zone, but a command pitcher has the ability to consistently hit the catcher’s mitt, preventing pitches from leaking out over the plate where major league hitters can do damage.

“He's always had the ability to throw strikes,” Carlson said. “So now, it’s attention to detail, how we practice, how he throws sides, how he attacks a game plan. To his strengths, let's just say he's stronger to one side than the other, then alright, let's nail that and occasionally hit the other side. So you start using the things to your strengths and to your advantages.”

Mantiply’s transformation began last season. After being called up in May, he established his position on the major league roster with a string of strong appearances while the rest of the Diamondbacks’ bullpen was injured or underperforming. Although Mantiply admitted, “still to this day, every time I have a bad outing, I'm looking over my shoulder,” that ability to work through rough patches without being sent down to Triple-A helped him get comfortable facing major league hitters.

This year, he’s taken the next step — buoyed in part by the addition of veteran closer Mark Melancon, with whom he’s settled into a routine of daily catch play.

Because relievers can’t throw regular bullpen sessions like starters do, pregame catch is the most important part of their daily routine. “That's the only time we get to really work on our craft,” Mantiply said. But it’s easy, Mantiply added, to just go through the motions as pitchers bide their time until first pitch.

Melancon, who has pitched in the majors for 14 seasons, doesn’t fall into that trap.

“Watching him, how he takes a lot of pride in his catch play and his preparation so it kinda forces me to do the same,” Mantiply said.

So now, in those pregame sessions of catch, Mantiply focuses on how the ball is coming out of his hand. If the feeling is the same every time he releases it, he knows his mechanics are sound and he’ll be able to spot the ball where he wants to.

“The ball will kinda tell you what you're doing mechanically depending on where it's going,” Mantiply said. “So if everything's working on time, the ball should go where you want it to go.”

Mantiply’s ability to locate his pitches where he wants to has combined with the natural movement he’s always had. His average sinker velocity of 90.3 mph is a relic of a bygone era, sitting in just the 12th percentile league-wide — an especially striking sight coming from a 6-foot-4 left-hander who looks the part of a fireballer.

It’s effective, though, because of its movement. Among 243 pitchers who utilize sinkers, Mantiply’s has the ninth most horizontal break. His changeup is also in the top 10 percentile league-wide in terms of movement.

“His ball goes east to west,” Carlson said. “… A lot of (teams) were chasing after the guys that threw 95-plus and Joe was a guy that, he's different than other left-handers all throughout … the league. You get a lot of guys that can throw hard with a lot of hop and his fastball is average, but his movement is plus so that's one of the things that made him stand out to us.”

Two years after he originally signed, Mantiply has succeeded beyond even the most ambitious projections. When asked whether the Diamondbacks knew he could be this effective, Carlson responded simply, “We hoped.”

It’s not long ago, Mantiply notes, that he wasn’t sure how much time his baseball career had left. In the winter of 2019, he was working back from Tommy John surgery as a minor league reliever with 5 2/3 career innings in the majors. That’s not a profile that makes a pitcher an organizational priority.

“The hardest part is just seeing the end of your career is closer than you think,” Mantiply said. In three months after returning from injury, he was traded from the Reds to the Yankees, called up, designated for assignment, passed through waivers, assigned to Triple-A and released into minor league free agency.

“I was hoping to just get a job here and there and put myself in a good chance to get a good opportunity,” Mantiply said.

With the Diamondbacks, he has.

Theo Mackie covers Arizona high school sports, the Arizona Diamondbacks and Phoenix Rising FC. He can be reached by email at theo.mackie@gannett.com and on Twitter @theo_mackie.

This article originally appeared on Arizona Republic: D-Backs' Joe Mantiply has been one of baseball's best relievers