Every BCS football player is on a 5 year ride. The money is there to do it, and that is the difference.
Remember that BCS Football (in NCAA Division I) is a non-equivilency sport. Translated, that means that football scholarships are all or nothing : there are no partial scholarships in football permitted by NCAA guidelines. So, it is a mistake to think about football scholarships in the same way that you would consider soccer or lacrosse scholarships.
The NCAA allows for 85 scholarship positions for a fully funded NCAA Division I team. If a fifth year student has a fourth (or extra) year of eligibility and the football program chooses to scholarship that player for their fifth year, that comes at the cost of an incoming freshman player being on a scholarship or at the cost of a mid-classman being cut.
