Danny Hultzen’s shoulder: What gives?

imageDanny Hultzen was drafted out of the University of Virginia in the famed MLB Draft Class of 2011 that included highly prized pitchers like Gerrit Cole, Trevor Bauer, Dylan Bundy, Jose Fernandez, Jed Bradley, Taylor Jungmann, Sonny Gray, Tyler Beede, Alex Meyer, and others who all would contest for a top three pick in any other year of the draft.

Hultzen was part of this class as well. He was certainly not a huge overdraft (if he was one at all) by the Mariners, though most considered Hultzen to have a limited ceiling compared to Cole, Bauer, Gray and Fernandez.

Still, Hultzen’s floor was considered to be very high as well—a guy who wasn’t quite a “can’t miss” pitcher, but one who should have comfortably settled into the big leagues on a fast track. He had what scouts considered a durable body and a short, clean arm action. He also was an exceptional hitter, which indicates all-around athletic ability. There were concerns about his arm slot (essentially side-arm/low three-quarters) and the fact he threw across his body slightly, but it wasn’t enough to move him down. (If Aaron Crow’s mechanics aren’t enough to move someone off a top three slot, no one’s mechanics are.)

In June 2011 I took a biomechanical look at Hultzen that didn’t allow for any subjective analysis—just kinematic analysis of video provided by various sources. What I noted was that Hultzen had typical ranges of kinematic parameters when comparing him to healthy and effective pitching mechanics of known populations:

However, with the nagging shoulder injuries that Danny Hultzen continues to suffer, it’s worth looking at his pitching mechanics from a more “subjective” viewpoint. By “subjective,” we’ll try to stick to widely available research as well as research our lab has produced that shows increased likelihood of undue stress on joints, and thereby possible increased potential for injury.


Hultzen’s mechanics have not meaningfully changed since entering pro ball:


But as many have noted, he has deflected his stride landing spot significantly more to the first base side of the rubber since his days in college.

“There’s pictures of me in college and pictures of me in pro ball and in college I was maybe a couple of inches across my body and now I’m maybe a foot or 15 inches. Maybe that was putting a lot of (extra) stress on my shoulder. Maybe it wasn’t but I think that had a lot to do with it.”

Let’s discuss the biomechanical effects of such a mechanical change.

Stride deflection – Hip

As the stride angle closes, it is more difficult to gain high levels of hip angular velocity. Since hip rotational velocity is strongly correlated with ball velocity, this generally leads to a reduction of fastball velocity in pitchers. Hultzen saw his velocity drop throughout 2013, though it was more inconsistent than it was a true loss of velocity. Additionally, a more closed hip angle significantly reduces the range of motion, which could have caused the hip strains Hultzen was facing throughout his pro tenure.

Stride deflection—elbow/shoulder

I think pitchers who have better “forward rotation” in their delivery tend to have more healthy pitching arms. We’ll focus on why this might be the case for the pitching elbow first.

Pitching elbow
In the still photo at the top of this article, it is pretty clear that the ball is released close to the torso if looked at from the side. Many call this an “early launch.” Research does indicate that a more extended elbow at ball release increases elbow valgus stress, as does early trunk rotation and a more sidearm delivery. (2009 Aguinaldo, Chambers, AJSM – link)

A good example of a pitcher with great “extension” (I really hate this term and I am not pleased that Trackman used it for this metric) is David Robertson. The very word “extension” implies an entirely linear component of getting the ball closer to the plate, but the reality is quite a bit different, as evidenced by what Robertson actually does.

Robertson - Pitching Mechanics

At ball release, Robertson’s shoulders have rotated well past “square” with home plate and continue rotating while the arm is internally rotating:

Robertson - Ball Release

This is the best example of “late launch” that I can think of in the big leagues—right up there with Trevor Bauer.


Hultzen lacks both the trunk forward flexion and the late torso rotation that Robertson and Bauer display, which causes extra stress on the…

A Hardball Times Update
Goodbye for now.

Pitching shoulder
Most of the increased stress on the shoulder is similar to that of the notes above about the elbow, but there is an additional issue due to deceleration problems with an early launch and body positioning. Since Hultzen’s body squares up at release AND his stride is deflected abnormally closed, it does not give him a good path for shoulder deceleration like you see in Robertson’s delivery.

Related to this is the fact that the hips displace his trunk in a disadvantaged position and artificially create a short deceleration path. The greater the distance over which the pitching arm can decelerate, the lower the peak stress on the joint. Remember, the pitching hand is moving at least 90 mph if the ball is being released at 90 mph, and all of that energy has to dissipate very quickly after a five-ounce ball is separated from the throwing hand.

What are the root causes?

Well, Hultzen’s deflected stride is only part of the issue. The fact that he has an abnormally short stride makes it hard to gain linear momentum to the plate, which would help increase trunk forward flexion and create a better deceleration path. The problem is that these mechanical changes are not simple to make, especially increasing stride length for someone who has somewhat unorthodox mechanics in the first place.

The prognosis for Hultzen moving forward doesn’t seem to be good, though fortunately minor damage to the shoulder is much easier to work on than damage to the elbow (the reverse is generally true when it comes to major injury). A comprehensive strengthening program—like the Mariners are tryingmdash;could help, but moderate mechanical changes are probably necessary to remove the red flags pointed out in this article.

And in my experience of working with professional clients, changing major mechanical concepts in someone’s delivery isn’t the simplest thing to do, especially when the parent organization doesn’t seek outside opinion. (But that’s a story better told over beers, now isn’t it?)

Kyle owns Driveline Baseball and Driveline Biomechanics Research, and has authored The Dynamic Pitcher, a comprehensive book and video set dedicated to developing elite youth baseball pitchers. He is also a consultant for an MLB team and a major Division-I college program. Follow him on Twitter @drivelinebases or email him here.

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