Just out of curiosity, why do you think they rotate DT's and DE's? My personal belief is that they know "fresh" players play better so they try to limit player fatigue. Pulling a DT out for a rest after 2 plays is not uncommon in college football. I can't get my DT to come out after 10 plays. That is the problem people are complaining about. (This is just an example using d line. The issue appears at every other position too. It's just most noticably here.)