Ray Lewis and Ed Reed were prima donnas, but they were players of character, not just characters. Michael Irvin and Randy Moss were high maintenance, but they produced on Sunday afternoons.
The NFL is full of superstars with enormous egos and crazed attitudes. But to win in this league, you need to have at least two or three on every team.
It's a fine line that NFL coaches have to walk, but the great coaches are able to control these types of players. And it's not just about coaching.