Umm... that's not how blocking schemes work. You can still totally triple team one defensive linemen in a 4 man front. Not to mention - he doesn't win 100% of the time against one on one blocking so technically, I understand why you say that but its not a guaranteed trade off... Teams for example could always chip with a tight end or roll away from him in a 4 man front, etc... most staffs would counter our counter so its hard to say for certain what would happen.
Its simple... the defensive line is TIRED. We have no seen any young ends until recently. And there for a while weren't seen a ton of Lee or Singleton at nose. Enyi, Will and Zach are exhausted. They have probably played about 90-95% of the snaps this season. I never coached at a big college but I know enough to know that if you're going to ask 3 defensive linemen to play almost every snap or that close.... they are going to be gassed at the end of the season.
I don't know if the other young ends are all that far away from developing or what but those three guys are gassed. I was certainly never good enough as a player and never rose to a high enough level as a coach beyond NAIA but the punishment a defensive linemen takes is a mini-car wreck almost every play where you have 300-600 pounds slamming into 50-60 times.
That's the main reason IMO the rush defense is starting to lag and the pass rush is not that great. We have 3 really good proven guys and we ride them but they are exhausted at this point in the season. If we could get another young end out there for 10-15 plays the last two weeks I am pretty sure that unit would play better. But if no one else is ready, then we're just kinda stuck.