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2019 Arizona Diamondbacks Reviews: #32, Jon Duplantier

Los Angeles Dodgers v Arizona Diamondbacks Photo by Christian Petersen/Getty Images

Rating: 4.94

Age: 24

2019 Stats: MLB 36.2 IP, 15 G - 3 GS, 1-1, 4.42 ERA, 3.95 FIP, 1.555 WHIP

2019 Salary: Minimum

2020 Salary: Pre- Arb Minimum



Jon Duplantier was a 3rd round draft pick out of Rice University in the 2016 draft. The big right hander (6’4”, 225 lbs) showed a lot of upside with a mid 90’s fastball and good changeup and curve. HERE is a good scouting report heading into the 2016 draft. However he missed all of 2015 with a shoulder impingement. From that report linked:

There’s little question about Duplantier’s ability: he could develop into an above-average starter or a power closer. The main doubt is health: Rice pitchers have a reputation as ticking time bombs when it comes to injuries, and Duplantier has already missed a year with shoulder trouble.

Indeed, he pitched only 1 inning for the Dbacks Hillsboro affiliate after the draft, and was shut down immediately with elbow soreness. However he rebounded with a dominant season in 2017, making 24 starts, and throwing 136 innings and posting a 1.39 ERA across two levels, A, and Advanced A. He was nearly unhittable, allowing just 6 Hits per 9 and 0.4 HR/9, while Striking out 11 per 9.

This rocketed him up to the top of the Organization’s prospect rankings, and he started off well after being promoted to AA in 2018. In his first 7 starts he had a 2.52 ERA and a 40/11 K/BB ration in 35 IP. But the injury bug struck again, as he was shut down for two months with biceps tendonitis. He returned to finish out his season well, but only pitched 74 innings in 16 starts total, so was sent to the Arizona Fall League to get in some more work. He did well there, and I mostly liked what I saw, which you can review in game reports HERE and HERE. This was my summary:

This is the 4th time I’ve seen JD pitch now, and I feel like he is already able to get major league outs. His fastball is usually around 95, ranging 93-96, and he has had trouble spotting it the last few times I’ve seen him. Even when he does, hitters can make contact on it and hit it pretty hard. It’s his breaking pitches that set him apart. They are sharp, and he has been throwing them over or around the plate, inducing a lot of swing and miss from them. With a little better fastball command to set up his breaking pitches, JD is capable of dominating.

This has been a lengthy “introduction”, but I think Dup’s history is important to review before moving on to his 2019 season. Hat Tip to Michael McDermott who helped me review some of his injury history.



Duplantier did not make the rotation out of spring training, but thanks to the pitching staff and bullpen getting shellacked in the opening series in LA, the team immediately needed an arm, and they called up Duplantier on April 1st. It could not have gone any better. He relieved Merrill Kelly with the team holding a 9-3 lead, and proceeded to throw three scoreless innings, allowing just 1 hit, striking out 2, and not walking a batter. A pretty cool foot note to that game was that Kelly (win) and Duplantier (save) became the first duo to earn the victory and pick up a save while making their Major League debuts in the same game.

He made one more relief appearance on April 7th and then was optioned down to Reno ostensibly to begin building his workload as a starting pitcher. It didn’t quite work out that way though. He made three short starts for Reno, never getting past the 3rd inning, before being recalled again on April 28th. He threw 4 more scoreless innings against the Cubs, and then was sent down again. He made an aborted start for Reno on May 4th, and failed to get out of the 1st inning, walking three batters. He was recalled to reliever again, and then sent down again. This pattern repeated itself throughout the season. In all he was called up 6 separate times. He did make 3 starts for the DBacks in one of those callups.

He once again encountered the injury bug, and had to be shut down for one month due to a sore shoulder. Perhaps it was due to being called up and sent down so much, or shuttling between starting and relieving, but as the season wore on his command got wore and his velocity dipped. The sharpness to his breaking stuff wasn’t really there, and he kept falling behind in counts and then started to get hit hard when he came into the zone with his fastball.

You can see clearly in the graph below, the velocity he showed in the fall league in October and in spring training, waned soon after being recalled multiple times, and then dipped all the way down to about 91-92 by the second half of the season. You can also see full table with game by game velo numbers HERE

In all, Duplantier only threw 80 innings in 31 games, 17 starts Majors/Minors combined. He never threw more than 5 innings in any outing, and he did that only twice.

It’s easy, even tempting to point to the multiple call ups and demotions and flipping back and forth between starting and relieving as the primary cause of his inconsistency, shoulder soreness, and drop in velocity. It certainly was a very strange way to handle a pitcher with both his in jury history and his pedigree. It seemed like the team was torn between wanting to continue his development as a starter, and utilizing a good arm in the midst of a wild card drive.

2020 Preview:

Perhaps the team will consider converting him into a late inning power reliever. He seems to have good poise and mound presence. Perhaps he can handle late inning pressure. How he would respond to relieving is anybody’s guess. The velocity dip is concerning. Perhaps relieving allows him to get back to the mid 90’s.

The bottom line is Dup turned 25 on July 11th, and will be 26 by the middle of next year, but seems no closer to being able to handle a starters workload. He simply has not been stretched out and proven he can be a guy that will at least complete 5 innings regularly and get into the 6th or 7th inning once in a while. He can’t even be counted on to go 5 yet. He has less than 300 professional innings pitched.

At this juncture, we have not heard anything about him being converted to a short reliever. But the 2019 season has cast at least some doubt on his future as a starter. It would seem, if it doesn’t happen early in 2020, then relieving is his future calling.