Probably because "ceiling" is usually misleading, if not complete garbage, once players have had time to be judged on the NFL playing field. Generally speaking, "ceiling" refers to unfulfilled potential that the beholder thinks he/she sees, and is almost always based upon the measurables that so many failed prospects have had. Arguing "ceiling", JaMarcus Russell should still be in the NFL, because his "ceiling" is higher than Tom Brady's.
