Denver Broncos
RBs
CJ Anderson shows high levels of anterior efficiency- in particular, his anterior thighs show strong independence, fast response time, and muscular strength. His high levels of anterior thoracic efficiency (for an RB) translate into soft, reliable hands.
Anderson borrows slightly from lateral towards medial areas (developmental pronation of the hips/ shoulders). Anderson’s posterior lumbar area also appears somewhat under-developed, particularly below the thighs. From his knees downward, there appears little independence and relatively slow response time (particularly in the lateral areas).
Given his lacking posterior development/ efficiency and constant pronation of the posterior hips, it becomes easier to understand why Anderson has struggled to stay healthy in the past. Although he currently appears as healthy as ever, it seems likely that he will struggle to avoid injury for a full 16-game slate. However, while healthy, he shows strong straight-ahead burst with powerful thigh action, soft hands, and quick feet.
De’Angelo Henderson also shows very high levels of anterior lumbar efficiency- higher than Anderson’s. In addition, while he appears to favor anterior efficiency over posterior efficiency, his medial posterior area appears fully developed. So, while he seems to lack some of Anderson’s thigh-strength, Henderson appears far more likely to stay healthy (due to a fully-developed core (medial) posterior lumbar area). Also, he shows reliable hands catching the ball, showing good medial-thoracic efficiency (for the position).
Henderson’s central-posterior efficiency also translates as excellent balance and ability to spin in either direction while maintaining equilibrium. Likewise, he shows sharp cutting ability. However, due to his small size/ stature and anterior focus, he does not appear to possess elite tackle-breaking ability. If the o-line is generating push, Henderson seems likely to be a very effective runner, with excellent quickness and good balance/ cutting ability. But he probably won’t be running through loads of tackles/ imposing his will on the defense.
To study Jamaal Charles is understand the make-up a Hall of Fame-caliber running back. Even now, after multiple ACL tears/ surgeries, Charles shows extremely high posterior lumbar efficiency, and good medial-anterior lumbar efficiency. He also shows very tight lateral-anterior mechanics, which is not a surprise given his injury/ surgery history. But even at this late stage in his career, Charles shows some of the most overall-efficient lumbar mechanics I’ve studied (and his posterior thoracic area also appears very efficient for the position).
Given his clear lateral-anterior weak points, Charles should probably be treated like an aging supercar- offering an incredible advantage whenever taken out of the garage, but always presenting a risk to break down. If Charles can be managed/ kept healthy, he will likely add tremendous value to the Broncos offense whenever he is on the field.
QBs
Trevor Siemian remains a difficult player to project, even in his second year starting. His anterior forearms remain highly efficient, allowing him a very accurate flick of the wrist with the ability to add spin/ subtle adjustments to his throws. However, Siemian’s posterior shoulders still appear under-developed. In addition, Siemian’s end-of-season shoulder surgery has left its mark, and his posterior shoulders now appear mechanically linked (more than ever).
Although Siemian shows very fast visual-recognition skills, his need to prepare each throw via posterior compensations means that his delivery often becomes longer than optimal. In addition, if he is disrupted after he begins these compensations, his throwing trajectory loses its fundamental accuracy (with the throw often missing high).
Siemian’s under-developed posterior shoulders make me question his season-long durability. QBs often take hard hits to the shoulders (especially when being driven to the ground), and Siemian’s taut posterior shoulders (seemingly lacking independence), significantly heighten the likelihood of further injury to this area.
Nevertheless, Siemian has shown remarkable mental/ physical learning rates since entering the league. If he can manage to stay healthy and ahead of his sometimes-slow delivery, his natural smarts and leadership may still prevail.
Before discussing Kyle Sloter, it may be helpful to re-visit the biomechanical review of Garrett Bolles (linked in the comments below). In that post, I explained how functional efficiency is not always the same as stable efficiency. The body has the ability to biomechanically “borrow” from one area to another, adding efficiency to one area while subtracting it from another (in Bolles’s case, he appears developmentally pronated in both thoracic and lumbar areas, favoring medial over lateral efficiency, and likely putting a cap on his maximum overall strength).
Kyle Sloter shows a very efficient posterior-thoracic delivery. However, he “borrows” so heavily in order to achieve this efficiency that his delivery is very constrained in its flexibility. Because there is so much tension from Sloter’s lower areas when he throws, the ball leaves his hand at a very low point, allowing defenders opportunities to knock down his throws at the LoS. In addition, Sloter shows sub-optimal anterior efficiency, which translates as an inability to put touch on his throws. Certain ‘flick of the wrist’ type throws (like screens, short dump-offs, etc) appear very difficult for him to master.
Sloter shows talent with his high levels of posterior thoracic efficiency. However, John Elway has shown a clear pattern of favoring anterior efficiency (Osweiler, Lynch, Siemian) over posterior efficiency. And through the lens of anterior throwing-related efficiency, Sloter appears decidedly subpar.