To be honest, I think that can be too high, especially if there is a big disparity between the starter and backup. All you need is inept or higher. If you are worried about stamina drops, then mediocre/average would be the way to go. Also, you have to factor in the offenses you run. If you have a fast-paced offense or defense, (LI, RNG) (1-3-1, FCP) then you need at least mediocre stamina on everyone. If you run normal-paced offenses, (Base, PTB, Motion, Iso Offenses) then inept or better. For slow-paced offenses, (LP, Patient, Princeton) then you can get away with bad stamina.