Fantasy footall week 11 question?

Correll Buckhaulter is questionable for week 11 (knee) is he is unable to play should i start knowshon moreno (will be the only runningback vs SD) as my flex or keep pierre thomas there who is facing the 31st ranked rushing defense in tampa, pierre is splitting carries with mike bell and reggie bush who also might be out with a knee injury!! please advise