Siemian reminds me of Montana.  I know that comparison is sacrilege.  But Montana had the same slight build as Siemian (not built to take a pounding).  Cerebral QB not known for a strong arm.  Montana was all about timing, getting the ball at the right spot so receivers can run after the catch.  Kind of similar to Manning.  I think with more reps, Siemian has the potential to develop into a strong QB.  Siemian needs a coach and front office that believes and trusts him.  You cannot keep yanking his chain and make him look over his shoulder all the time wondering if he is going to get replaced if he has one bad series, half or game.
It is obvious Lynch is not ready.  So put your trust in Siemian, give him the majority of the snaps before the season starts and roll with him.