I won the Iron Bowl without ever training stamina.

viktor wrote: If at all you subscribe to the 'Stamina is important' theory : Stamina has equal importance for all offensive and defensive positions. The amount of stamina that helps sustain a certain level of play depends on the level of play. A guy with a staring rating 3.5 does not need more than 6-7 in stamina. BTW stamina caps at 20 for all players ....so I would say training time spent maxing it out would be better used training some other skill

Agreed.........stamina looks nice, but it's been proven by many top level teams that it isn't necessary for the elite players

I scout top teams and follow the trends in their player skills. Very few of these teams have high stamina players but I just don't like using players with low stamina, this is just a feeling I've had since about season 2 - no real evidence to back it up.
At the moment 17 of my starting 22 O & D players have stamina of 10 or above. Did this help me last season? I really don't know for sure. I did win a couple of important matches late in the 4th quarter but this could have just been the result of other game variables and not stamina.
I've asked a question in the Q&A input thread about stamina (and about energy), hopefully there'll be some sort of response.