The discussion of Jeremiah Smith's touchdown led me to revisit the NCAA rulebook.  Maybe I'm missing something, but I think if you take so literal an interpretation as the TV analysts did, then the famous Vince Young touchdown against USC (and likely countless other touchdown runs to the pylon) should have resulted in a touchback.

The rules state: 

• "To fumble the ball is to lose player possession by any act other than passing, kicking or successful handling. . . . The status of the ball is a fumble."  FR-36.
• "The ball is in player possession when a player has the ball firmly in their grasp by holding or controlling it with hand(s) or arms(s) while contacting the ground inbounds."  FR-33.

The analysts asserted that any time a player already in possession does not have firm control (whether Smith lost control is debatable in my view), then the player has lost possession and a fumble has occurred -- even if the player does not lose the ball.  I suppose you could read the rule that way. 

But the other requirement of the same rule is that the player must have control "while contacting the ground inbounds."  Applying their logic, any time both feet are off the ground (which happens several times in most runs), there is a loss of player possession and therefore a fumble.  There would dozens of inconsequential fumbles each game recovered by the runner.  

But suppose that a QB runs to the pylon and leaves the ground right before the ball crosses the goal line and then first lands out of bounds (the ball having crossed the goal line in bounds).  Under the analysts' interpretation, the runner would have lost "player possession" upon ceasing contact with the ground and the result would be a fumble without repossession in bounds.  That's just wrong, and the booth was right to uphold the call on the field.