I also think it's interesting to compare Josh Allen to Carson Wentz. Both were huge, athletic white guys from small-time colleges, both had every physical tool in the bag, but had shaky accuracy and some bad decision making habits.
Allen has plainly grinded like mad on his game, and after a questionable first two years, he exploded into a star. I can't think of another player whose completion percentage rose so far from college to the NFL.
Wentz refuses to listen to coaching and refuses to stop playing hero ball, and so he's basically never progressed since he left North Dakota State. Now he's a coach-killer on his 3rd team whose career is circling the drain. Allegedly, a Washington DE chasing him down in practice starting yelling "throw the ball away!", and Wentz still ran out of bounds. He has MVP level talent like Allen does, but he just either doesn't care about ball or is too arrogant to play on anything but his own terms.
