I was speaking more on the HS level especially in the area I'm in. I have no clue how Miami practices are run other than the quick clips I see from reporters.
Here is a good article on how rules changes have impacted practices at the D1 level
https://www.si.com/college/2021/05/05/ncaa-football-fall-camp-changes-safety
"At an Oversight subgroup meeting on Wednesday afternoon, committee members are expected to finalize the modifications. While the new rules keep the number of preseason practices (25) over the same amount of days (29), they regulate the type of practices coaches can hold.
The new system is being referred to as an 8-9-8 model: eight practices in helmets, nine in shells (helmet and shoulder pads), eight in full pads. Under current rules, coaches are required to hold the first two practices in helmets and the next two in shells with the remaining days unregulated.
Most coaches do not operate 21 days of full pads, but some hold as many as 21 days in at least shells. For many, the new policy is a difference of two to four practices in only helmets rather than shells.
“For us, it will impact a couple of practices,” says Troy Calhoun, the longtime coach at Air Force who says he normally has his team in full pads or shells in about 19–20 days of camp."
In shell you cannot tackle to the ground
From when I played college ball 5 years ago thats pretty different than what we had.
I know on the High School level we can't do two-a-days anymore unless the second practice is a walkthrough.
When it comes to in-season practices, I have no idea what the rules are for that, but yes Pete Carrolls standard of tackling does require you to go to the ground. I have no idea how Miami would practice it without going to the ground haha as a Coach though I would want to dramatically limit the amount of times guys touch the ground tackling each other in-season.
I'm not defending Diaz or saying he should be here. All I am saying is that the game is dramatically different than it was 20 years ago. Mordern Problems, modern solutions. I'd much rather be able to do it old school, but you can't anymore.