The WSJ reports that the NFL Eagles mainly draft college graduates. Why? Isn't the NFL a "muscle" rather than a "brains" league? Graduating from college requires certain non-cognitive skills that Jim Heckman has written about in many recent papers. In a simple signalling model, obtaining a college degree may signal to coaches a willingness of the player to persevere and go to Econ lecturers (rather than party) and at least moderate intelligence. An imaginative coach can have a more sophisticated playbook if he knows that his players will be able to understand and execute the plays.
Whether the "Big 5" personality traits embodied in individuals aggregate up into a winning football team is an open question. For example, there are 22 starters in football. Is the starting team's overall perseverance a function of the team average for this personal characteristic? Or is it a function of the player with the most perseverance or the least perseverance (an O Ring theory of the team that you are only as strong as your weakest link). See page 141 of this Todd Sandler paper.
Teams also worry about discipline and players staying out of trouble. What are the facts? Are the NFL's college graduates less likely to be arrested than the average player? If the answer is "yes", then this is sharp evidence that the college graduate subset have higher average non-cognitive skills of self control.