In order to understand why Pat Shurmur’s offense has not, to date, been a good fit for Drew Lock, it is helpful to first conceptualize the entire fascial system as a sort of bendable sheet overlying the musculoskeletal system. This sheet (which feeds blood and removes waste) has major junctions of its own which, when aligned with the corresponding underlying skeletal/ muscular junctions (such as at the transitions between spinal areas), allow instant action and quick bloodflow (assuming full development of the underlying areas). However, when major fascial junctions are not aligned with their underlying musculoskeletal junctions, bloodflow slows and muscles contract/ release much more slowly.
This fascial sheet, while stretchable, is not long enough for every major junction to be correctly aligned at the same time (due to incomplete development in some areas); when one underlying muscular area is being utilized, it pulls the sheet towards it, potentially misaligning distant junctions. So, for example, if a person is naturally posterior/ thoracic dominant and they are asked to continually engage their anterior thigh muscles, this muscular action will pull the sheet from the posterior/ thoracic areas towards the anterior/ lumbar areas (the path of the sheet movement being up the back, over the shoulders and then down the anterior towards the lumbar areas).
The example given above is taken specifically from Drew Lock’s passing stance in Pat Shurmur’s offense. Shurmur’s QBs, both previously and currently, utilize a passing stance where the anterior thighs are continually engaged and active. This passing stance is very beneficial for certain types of QBs—by keeping the knees bent and thighs engaged, the feet are given constant bloodflow and are therefore able to quickly pivot to different horizontal angles, allowing the passer to quickly shift their horizontal throwing plane. In addition, by pulling the fascial sheet from the posterior towards the anterior (ie borrowing from the posterior), overall anterior efficiency is increased, in both thoracic and lumbar areas. “Borrowing sheet” from the posterior allows anterior fascial junctions to better line up with their underlying anterior musculoskeletal areas, providing increased bloodflow, faster response times, and quicker waste removal. In practical football terms, this knee-bent thigh-active passing stance speeds up quick horizontal shifts of the anterior system, allowing a passer to more quickly shift between different horizontal receiving options.
For anterior dominant QBs, this passing stance is very beneficial—it maximizes their anterior efficiency by aligning their major anterior junctions, and speeds up their ability to pivot and accurately throw to different horizontal targets—a major plus in Pat Shurmur’s horizontal misdirection offense. Historically, almost all of the Pat Shurmur coached QBs were anterior dominant, and many of them saw their level of play increase substantially in his system and with his passing stance.
However, Drew Lock is not anterior dominant: he is lateral-oriented posterior dominant. And while his lateral posterior thoracic areas are fully efficient (meaning that his lateral posterior musculoskeletal areas are fully developed), Drew Lock’s anterior areas are distinctly underdeveloped. Because these underlying anterior areas are underdeveloped, even when the sheet is pulled towards the anterior and the anterior fascial junctions are more or less aligned, full efficiency does not result— when the structural musculoskeletal areas themselves are stunted, increasing the blood flow will only help muscular response to a relatively small degree. Developmental stunting means that full efficiency is not possible, and pulling sheet towards it will only help so much.
In addition, by borrowing sheet from the posterior towards the anterior, Lock’s natural full efficiency in his lateral-posterior areas is discarded—as the sheet is pulled towards the anterior lumbar areas, the sheet’s major posterior junctions lose synchronicity with their underlying posterior musculoskeletal areas. What was previously fully efficient in lateral lumbar areas becomes inefficient as the sheet is stretched and the posterior junctions misaligned.
Take a look at the two videos below—one is from Drew Lock this year, one is from Drew Lock last year. These differences are subtle, but notice how in the 2019 video, Lock is mostly standing straight and tall, and when he release the ball, his wrist goes limp afterward (similar to famous jump shooters like Ray Allen, Reggie Miller, etc)? This limp wrist is because Lock’s anterior areas are mostly slack, only engaging for small corrections or adjustments to the throw. This is what Drew Lock’s fully efficient throwing mechanic looks like.
Contrast that with the 2020 video—Lock’s knees are slightly more bent, his anterior thighs are engaged, and when he throws the ball his wrist is tight and engaged throughout—this is because he is now driving the ball with his ineffiecint anterior system, rather than his fully-efficient lateral posterior system (Lock’s stance is also subtly shifted to be slightly more horizontal to the line of scrimmage). Shurmur’s passing stance has forced Lock to use his weakest areas to throw, as opposed to his strong and fully efficient posterior areas.
There are very good reasons for Shurmur to teach this passing stance to his QBs—his passing offense is predicated on horizontal misdirection; he gets the defense moving in one direction, and the has the QB quickly adjust and pass in the opposite direction (this is in contrast to Shanahan-tree offenses, which generally stretch defenses horizontally with the run game while using vertical misdirection in the passing game). Shurmur’s preferred passing stance favors quick horizontal pivots, and reflects his offensive philosophy of horizontal misdirection/ isolation. It’s a very effective pairing of mechanics and offensive scheme. The problem is that it exacerbates Drew Lock’s mechanical weaknesses (underdeveloped anterior), while hiding his strengths (fully efficient lateral posterior).
The Shanahan-tree QB stance is hardly perfect– by placing QBs slightly more perpendicular to the LOS and asking QBs to plant off their feet (engaging the posterior thighs rather than the anterior ones), Shanahan QBs sacrifice some horizontal range in favor of greater vertical accuracy. And the deeper the throw, the more flexibility is needed from the anterior system, so anterior efficiency is still relevant/ important.
But in Drew Lock’s specific case, the Shanahan stance maximizes Lock’s natural strengths by organizing throws around the lateral posterior areas (which for Lock are fully efficient), rather than the anterior areas as in Shurmur’s offense. And while Drew Lock’s deep accuracy was gated in Shanahan’s system by his tight/ underdeveloped anterior areas, over time and with more biomechanical development, this anterior flexibility would likely have been generated, since it would have been organized around a fully efficient baseline mechanic (much like how Dak Prescott was able to greatly increase his deep accuracy over time). By stretching the sheet from a fully efficient place to a less efficient place, overall blood flow of the entire system is much more efficient, enabling much faster development of distal areas.
This has been a deeply technical article, and the differences on video are subtle. But try the two different passing stances yourself to see/ feel the difference. Grab a throwable object, stand directly in front of your intended target (parallel to an imagined line of scrimmage), bend your knees and keep your front thighs engaged. See how that brings your anterior system together for a throw, with your chest/ under-forearms engaged? Do you feel how quickly you can pivot to hit different horizontal targets?
Next stand more sideways to your intended target, push down with your feet and throw. See how that brings the muscles of your back more into play, with the ball being powered more by the pinky (lateral) side of your hand? Do you feel how this stance optimizes your vertical accuracy, but that it’s slower to pivot to different horizontal targets? And how the more you can stretch your chest upward (anterior flexibility), the deeper you can throw?
The first stance is a gross approximation of Shurmur’s baseline stance, the second an approximation of Shanahan/ Kubiak’s. And unfortunately for the current Broncos, the second stance is a far greater fit for Drew Lock’s biomechanical makeup.