I think Dabo's stock took a hit this year. Lots of kids transferring out, some controversy about playing a kid that almost killed a mail carrier while speeding, proof that his success at Clemson has mostly been down to him surrounding himself with very good coordinators. Only way he leaves is if he's sure he can do the same wherever he goes, and Bama isn't coming open at the moment, unless Saban decides to really shake things up and retire.
They're still the winningest program in college football history with a massive fan base. They're definitely tier 1.
The only thing I can figure is that LSU parked a few Brinks trucks on his front lawn and he thinks LSU is his only shot to win a national title before he's done.
Notre Dame is currently in the middle of their best couple of recruiting classes since forever though, so it's still crazy to me that he's leaving... aside from the money angle.