2 cents.
The two big IU improvements that stand out to me:
1) TACKLING: No weak arms. No juked and falling over empty handed.
2) A PLAN/UNDERSTANDING: No one looks lost. No silly mistakes (like bumping your QB and causing a fumble)
This second one, I think, is big. Winning programs always seem like they know the exact script of the game, then just execute. It seems they know what the opposition will do-- not just the coaches, but every on-field player and execute accordingly and it looks easy. Having rooted too many times for the rube in those kind of games, it's nice to be on the good side of it.
I think those two things are part of it...but my very strong feeling is that its much more foundational, and granular than those things.
Allen's teams tackled well, at times. They often came in to games on fire, and one would have to concede their initial game plans were solid, a lot of the time. But all too often, that energy faded, the execution faded, other teams adjusted, IU didn't.
I put the reason for that on the types of things Cig is likely focusing on and demanding versus what Allen did.
All coaches have routines, various drills they work on, etc... But most coaches and programs have a common driving force behind their daily actions. Allen's was famously LEO...it was based in emotions, lots of cheerleading, lots of yelling and hooting and hollering. I think those things masked serious deficiencies in granular levels of execution. And when other teams matched their emotion, when they changed game plans around, when unexpected things happened...that caused their own energy to fade, they didn't have foundational execution abilities burnt in to their muscle memory.
Cig has Saban's philosophies built in to his own approach. He's talked about it, and I'm sure it helped form what the driving force in his programs is. And that's know your job, do your job right, do your job right at the right time. And he's in the early stages of forging that in to his IU program. Tackling, blocking, running hard routes, hitting the right holes, holding contain, taking the right angles...all of these things are coached and demanded. So much so, that when the emotions change during games, execution will still be there. When officials make awful calls and starters get ejected, guys from the 2 deep come in and can rely on the execution burnt in to their DNA. We don't see entire parts of our team fold up like a cheap tent like they did when McFadden got ejected, or when Tennessee got their onside kick, etc...
We'll lose some games this year because we'll make mistakes, and then obviously because the other team has more talent. But its going to be more difficult for other teams to capitalize on mistakes and talent gaps, against IU now, than it used to be. Because they'll be facing guys that know their roles, are good at their roles, and are reliably executing within those roles.