During the off-season the-much-smarter-than-I clack wrote an article comparing Dallas Keuchel's 2014 to that of the 2003 and 2006 seasons of Brandon Webb. That prompted an idea from Tim for me to take a look at Keuchel's and Webb's mechanics to further that comparison. Nearly four months later, it's here.
Keuchel has always been lauded for having clean mechanics. The elbow doesn't rise above the shoulder as in the high elbow inverted W as described by Chris O'Leary (among others). He does have some subtle inverted W arm action as originally described by Paul Nyman.
Note: I just teased an article that I plan on writing soon with the two definitions of the inverted W. Just to keep people calm, the definition that O'Leary uses is the one associated with injury and Keuchel does not display it.
His delivery isn't considered "high effort" by any means. He doesn't fall off all over the place. He's not unbalanced.
However, he is a ground ball rate pitcher. There has been some suggestions that roundball pitchers have increased injury rates. That hasn't been completely supported by studies though.
The fear is that with such a similarity in stuff and rates as Brandon Webb, that he may eventually have the type of injury that cuts a career short. Brandon Webb had a great career that lacked the longevity that you might expect due to a significant shoulder injury. He underwent an arthroscopic shoulder surgery and then eventually had surgery to repair his rotator cuff. Ultimately he would attempt a come-back but never regained the velocity.
It's important to remember that when it comes to injuries, mechanics aren't everything. Velocity isn't everything. Innings isn't everything. Pitch counts aren't everything. Training is not everything. For each player, it's a different blend of factors.
If you look at the lower half, these two pitchers are pretty similar. Both lead with their hips and generate a little knee and hip flexion to get the last final drive to the plate with the hip turn. Webb went into knee and hip flexion a little earlier but its not a big deal.
Keuchel breaks his hands a little earlier but they end up having similar arm actions. None of which appears to be too strenuous on the shoulder.
The aspect of the delivery that is very different for these two pitchers is the deceleration phase. Traditionally the late cocking phase was known as the most damaging. However, I consider the deceleration phase as a potentially more damaging phase. It requires a lot of eccentric strength and control of the posterior shoulder. It requires a good path of the arm to slow down. Otherwise the shoulder has to do a lot of work in a short time frame, and is usually unable to adequately do so. The result is stress to the posterior shoulder structures and can cause impingement of structures as well.
What safe deceleration requires is hip and trunk flexion and good forward rotation of the trunk so that you are releasing the ball closer to the plate. It requires good pronation of the forearm as well. Keuchel does very well with this as he rotates around his pivot leg and ends up pointing his torso toward third and his back parallel with the ground. Also his forearm is completely pronated and his palm faces first base early in the deceleration phase.
Webb on the other hand does forward flex his trunk but doesn't have much forward rotation. Due to not rotating well he lands nearly squared to the plate and actually his weight ends up shifting him back towards third base. That forces his arm to have to try to decelerate in a small path and across his body. That makes the posterior shoulder get stretched a lot and over work. He also tended to not pronate very well. His forearm was usually in a more neutral position through the deceleration phase. Traditionally, pronation and internal rotation are innately tied to an extent. Limited pronation sometimes can indicate limited internal rotation. Limited internal rotation is common cause for shoulder impingement and commonly limited in pitchers. However, this is not always the case and not to be taken as a fact.
Again, mechanics is just one aspect of injury risk. But, based on mechanics, Keuchel is a solid step ahead in the quality of his mechanics. So, despite the similar profile and an unconfirmed theory of extreme ground ball pitchers being more injury prone, Keuchel appears to be at less risk to take the Webb path of seeing his promising career abruptly end.