It depends on what you will be asking of the specific player. For example Robert Quinn is one of the best pass rushers in the NFL and he never took a real class while at UNC. It doesn't matter when all the system asks of him is Rob Smash QB. Its so easy a tarhole can do it.
On the other hand Quinn's fellow sham class mate WR Greg Little is struggling in the NFL despite his enormous physical skills. According to folks in Cleveland he has time management and maturity issues and simply could not learn his play book.
There are some positions and certain schemes where the players need solid study habits in order to be successful. experience can also be an enormous plus if it is spent in a program that can correctly develop players. On the other hand four years of practicing bad habits can be difficult to overcome.
Personally I'd love to see the NFL reward players who obtain actual degree's with some sort of exemption to their rookie deal or maybe one less year before they can renegotiate.