This is too narrow of a perspective. In the pros, having the arm and being touched by the hand of God -- and little else -- only gets a player so far.
A good comp from the 1980s: Tampa Bay Steve Young couldn't QB his way out of a paper bag. San Francisco Steve Young waltzes into the Hall of Fame.
Coaching matters. Not to turn pumpkins into stars, but to get the most out of both your pumpkins and your stars. Even the greats can be -- and have been -- put in poor positions to succeed.