Let's say you are correct about the coaches with elite athletes being able to exploit the defense, and I think you may be right. The sample size is getting too large to ignore. You aren't going to have elite experienced athletes at every position. Other schools are recruiting too and people leave early for the NFL. Wouldn't a shift in philosophy to try and come at the offenses differently be in order?
We can go back to 2012 to see when Saban began shifting to speedier if slightly less bulky LB's and even on the DL. It seems we got away from that just a bit and it's biting us now.
Do I think a shift is needed? Yes, I do to a degree.
It would be great to have some different packages but with the substitution rules as they are now that is not going to happen in the game.
Fundamentally there is not much wrong with the defense Saban runs, though it does have vulnerable points. That said, with modern offenses and especially with modern QB's able to exploit those weakness with elite athletes around them it is my opinion (and has been going back to at least 2016) that the defense has to either change to something more simple or be more multiple with both schemes and personnel. The problem with being more multiple, again, is the substitution rules. However, since if the O substitutes then the D can also that may help with the platooning needed for such a multiple defense. I understand we do run multiple variations in this scheme and don't mean to imply we don't.
We also have to get rid of the substitution mistakes. I'm not sure who that's on but that has to be corrected. As someone said earlier, managing minutes played is something that may need to be looked at, even if it means not always having our best on the field. There are ways to mitigate the damage that would cause, but it would cause damage. More damage than everyone getting completely worn out? I don't know.