I think I first mentioned this about two years ago. Dunno know when.
Kirby is not comfortable according to what I've been told from people around the UGA program. I'm paraphrasing here when I say "Kirby's obsession with Bama has only intensified since Saban retired."
There's a really easy answer here as to why. What do Kirby, and his defenses, have a hard time with? A mobile QB, who can hit a deep ball. Kirby knows his DB's will be out-schemed. Their only hope is stopping the running game. I don't see that happening for four quarters.