To a degree, everything is coachable.
Unfortunately, most things are uncoachable at this point in an athlete's career. The odds of Darnold's egregious throwing mechanics drastically improving are slim to none. A lifetime's worth of bad motor patterns are ingrained so deep into his nervous system that it's nearly impossible to overcome them. Not to mention that they're only being further reinforced in each game he plays.
This is why Kap couldn't change his mechanics no matter how much time he invested during the offseason. He's trying to amend 25+ years of bad motor patterns in a couple months. It's not happening. When the bullets fly, humans revert back to what is natural for their individual nervous system.
Luckily, it's a non-issue for us. I see no scenario where we draft Sam Darnold. Not only is Sam's style of quarterbacking a departure from Kyle's QB archetype, but I can't see Kyle wanting to draft a guy he has to re-teach to throw before he can begin learning his offense.
[ Edited by Heroism on Sep 9, 2017 at 10:25 PM ]