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This is a much, much different Justin Dunn...

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Justin Dunn needed a complete transformation and that might have happened...?

MLB: Chicago White Sox at Seattle Mariners Joe Nicholson-USA TODAY Sports

Let’s be totally honest here. The 2020 version of Justin Dunn was no more than a pair of Air Jordan 1 “Air Dior” bought off Wish.com. On the surface, it was, eh, a little convincing, but take a closer look and the seams were frayed, the midsole was too big and the swoosh was too thick and bloated. Make no mistake, the Justin Dunn of 2020 would have fallen apart had you laced him up a few more times.

The Dunn of 2021 is a different animal. He’s certainly not a legit pair of “Air Dior” Jordans, but he might be a pair of stock Air Force 1s.

Now that I have you totally lost, let’s put it this way: Dunn is now equipped to, at the very least, compete at the big league level.

The conversation starts with the body. To his credit, Dunn went to work this offseason diagnosing his weight gain struggles and the subsequent loss of athleticism in his game. He cut dairy after learning he had a slight allergy/intolerance, and began eating much healthier as a result. He changed his workout regime to better cater to his biochemistry as well. He’s experiencing less general inflammation and overall fatigue because of it. It’s easy to see the results just by looking at how Dunn is wearing a jersey this season. Having dropped 10 pounds this winter, he looks much more equipped for long innings on the mound.

Last season, Dunn was rigid. His actions on the bump lacked athleticism and fluidity. His windup became robotic at times, his delivery sputtered from checkpoint-to-checkpoint before eventually making his moving down the mound. The result was a loss in arm-speed and explosiveness. His flexibility, extension, velocity and overall stuff suffered.

Dunn’s average fastball velocity in 2020 was a career-low 91.2 mph. For a guy who was essentially a two-pitch arm, that simply won’t work. He was the beneficiary of extraordinary good luck, and that’s what buoyed his baseball card at the end of the year. But Scott Servais and Pete Woodworth sat down with Dunn and had a heart-to-heart conversation with him in the year-end exit interview. Dunn needed to reclaim his old stuff, his old body, and come back in 2021 a completely new pitcher. While nobody has outright said it, it should probably be inferred Dunn was pitching on borrowed time. If his stuff didn’t improve, a move to the bullpen or the minor leagues was one bad start away. That story played out well into spring training, Dunn eventually inching out Nick Margevicius to claim the final spot in a 6-man rotation.

But he’s earned the shot to stick in the rotation. At least for now.

Dunn’s fastball is back up to 93.4 mph this season and the surrounding metrics behind it are promising too. He’s getting 130 more RPM on the heater this season, up to almost 2400 RPMs. That’s above average spin. He’s also changed his arm slot from a 1:15 orientation closer to a true 1:00 slot. That will inherently increase riding action on the fastball. These changes have allowed Dunn’s heater to hop an additional 3.2 inches, a substantial jump.

Where Dunn must improve is commanding the pitch at the top of the zone. Too many heaters middle-middle. Worse still, a riding fastball at the knees center-cut can be even more dangerous.

This narrative is nothing new to Dunn. Control and command have always been a struggle and if he’s to remain a starter long-term, it’s one of the focal points he’ll need to continue to refine. Dunn’s walk-rate is actually up to 16.9 percent this season and that’s entirely unsustainable if he’s to succeed long term. In 2020, his 15.7 percent walk-rate ranked in the 4th percentile in all of baseball. He’s got work to do.

Fastball improvements aside, the reclamation of the slider is the most substantial development for Dunn this year. The velocity is up a tick, but the shape of his breaking ball is what’s most noteworthy. The slider has more two-plane break this season. That’s especially impressive considering he’s coming from a more vertical arm-slot. So really, the movement profile *looks* a lot more violent to a hitter than the HawkEye numbers will suggest.

Dunn’s spin rate on the slider is up almost 200 RPM this season, approaching 2550. Again, slightly above league average. But the arm slot tunneling off the fastball, as well as the command for the pitch has been impressive.

If Dunn can get ahead of hitters with the fastball, this sort of command will allow the slider to play “plus” and represents a true out-pitch.

But there’s still plenty of work to be done.

Right now, Dunn is effectively a two-pitch guy. He’s a fastball-slider pitcher and neither pitcher is so good that he can get away with hurling them until his arm falls off. You’d be hard-pressed to find many two-pitch guys in the league with his mix that find success long-term. Dinelson Lamet of the Padres is an example of a two-pitch fastball-slider starter, but his stuff is on an entirely separate tier from Dunn’s.

Dunn will need to develop a changeup, a hard cutter, or a much different curveball if he’s to find success over the course of 160+ innings. What we’ve seen from him thus far is encouraging, but the league will adjust and catch up to him. The Red Sox were in a very good spot last night attacking the fastball. Unfortunately for Boston, Dunn found exceptional command for his breaking ball neutralizing their aggressive approach. Without that command of the slider, the box score ends up looking very, very different.

Dunn is currently operating on a razors edge. His walk rates are unsustainable and he’s not striking out enough batters to be “effectively wild”. If he arrives at the ballpark without feel for his breaking ball on any given night, he just doesn’t have the arsenal to get through a lineup twice.

As it stands, Dunn still has a very real chance of realizing his back-of-the-rotation role long-term. He’ll need to add a formidable third pitch, but the possibility certainly exists. But maybe the biggest takeaway from what we’re seeing right now is Justin Dunn is probably a safe bet to fit in as a big league reliever. A year ago, I’m not sure even that floor was a tangible outcome.