Harry, with all respects sir, you might be able to fine tune a guy's throwing motion or stance but you are not going to significantly improve accuracy in my opinion. Now, if he is inaccurate due to difficulties in reading a defense or anticipation, I think you can actually teach that through repetition because it's not directly physical but mental and not rocket science (though for some, even that can take too long for the patience of a NFL franchise). Sometimes it's simply you are surrounded by a crappy supporting group, which can hinder accuracy removed from the QB's actual ability. The first you cannot as much as arm strength unless the team drafting Allen has a time machine and can go back when he first adapted his throwing approach. There has never been a QB who got better with accuracy to my knowledge. Heck, some of it has to do with what you cannot really see as the movement of the wrist and how it comes off the fingers. Sometimes the instincts from hand to eye coordination is just slow enough to not succeed as a pro
This is not baseball, it's a brutal contact sport and a guy cannot go to the 'summer league' and play three hundred football games and improve like a pitcher. Guys are coming in to take your head off regardless of the rules, and your instincts are going to revert to how you have learn since a pup on how to throw the ball while under duress, chaos which Allen cannot even phantom while playing at lowly Wyoming. Allen is not going to become more accurate if it has to do with his form throwing and by improvement, I am talking significant improvement to improve his crapalicious completion ratio from college
For me Ryan Lindley is a great example because it appears he is valued as a quarterback coach by some. The man knows how you are suppose to throw the ball, he teaches QBs. He has more than enough arm strength but yet he cannot change what he is, the bad habits are already in his DNA so to speak, a word our new coach likes a lot. I think Lamar Jackson has a better chance of becoming more accurate than Allen can, because I do not think his accuracy issues are totally arm related... I guess we will find out