Kyle Boddy is the founder of Driveline Baseball where talents such as Trevor Bauer have received advanced training and player development services. Kyle has penned pieces for numerous publications including Hardball Times. His blog can be found here.

Some time ago, I told a few people that I’d take a look at Tyler Skaggs’ mechanical changes that led to increased velocity in 2014, as noted by many sites like the LA Times and Fangraphs.

Tyler Skaggs' Velocity

However, I didn’t get around to doing this before Skaggs’ ended up needing Tommy John surgery. On a whim, I decided to finally follow through with my promise and take a look at his mechanics from 2013 and compare them to this year’s delivery.

Tyler Skaggs 2013 vs. 2014

(2013 on the left with the Diamondbacks, 2014 on the right with the Angels)

Both of these pitches are fastballs and out of the windup. The one on the left is theoretically his best bolt, since it’s an 0-2 fastball to Alfonso Soriano. However, the one on the left is 88 MPH and the one on the right (to open the game!) is 93 MPH.

The mechanical differences are pretty significant. The basic armchair view shows you that Skaggs had a lot more pre-pitch movement in 2013 with a strong overhand pump that cycled into his arm action, while in 2014 he kept the overhand pump (not seen in this video, but it was there) but scrapped trying to gain momentum into ball separation from the pitching hand and the glove hand. Additionally, you can see quite a bit more recoil post-pitch in the 2013 video, which is surprising given his increased velocity in 2014.

Here’s a more detailed analysis on the mechanical changes:

Release Point

Skaggs Release Point

Skaggs had a slightly lower release point in 2014 per raw PITCHf/x data, though the difference is minor.

Glove Side Elevation

Skaggs' Gloveside


Skaggs has significantly more elevation of the glove side in 2014, which allows him to leverage trunk flexion easier for increased translation speed, which probably contributed to his velocity gains seen in 2014. This is a generally good mechanical pattern improvement.

Spine Lateral Tilt

Skaggs' Spine Tilt

Skaggs has quite a bit more lateral spine tilt in 2014, which throws his pitching arm away from his body (which was already a problem in 2013). By driving the pitching hand away from the trunk at faster rates, velocity may increase, however strain on the elbow and posterior shoulder tends to come along with it. Again, Skaggs already had an “unbalanced” rotation phase, but it seems his attempt to throw harder exacerbated this particular mechanical flaw.

Followthrough / Glove Block

Skaggs' Followthrough

Though this frame makes it look like Skaggs does a better job with his glove positioning in 2014, it’s somewhat artificial. If you watch the video clip above, you’ll see he still has a significantly low glove position through rotation that firms up late. In general, I do not prefer a pitcher who has a “strong front side”  that is typically taught by the Tom House camp – one of the biggest changes I encouraged Trevor Bauer to make in 2014 was the “disconnection” of the glove arm from the pitching arm to create separation between both arms, as somewhat demonstrated by this clip of him throwing in my facility this past offseason:

Trevor Bauer Separation

Instead of the arms “working together,” I advocated that Trevor think about “folding” the glove arm into the body early to create small yet significant separation between his arms. Most pitchers today do not do this, instead having been taught to be “equal and opposite” as conventional wisdom holds.

At any rate, Skaggs actually does a much better job of complete rotation in 2014 as opposed to 2013, as you can see his left shoulder has rotated better into the target and his trailing leg has a greater height due to increased trunk flexion.

Wrapping it Up

Skaggs’ injury was certainly multi-factorial — it’s never just one thing. While I don’t think his set of mechanics in 2014 were that bad, I don’t believe his mechanics from 2013 were good either. Skaggs throws like a typical lefty in that he mostly “pushed” the ball to the target without using much rotational force driven around his glove side, though he started to make gains here in 2014. It’s possible the increased velocity added to an already flawed delivery was the primary reason for injury.

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