He'd be an interesting hire. This has the feeling of a "legit rumor" as well. I was 100% in favor of going after Mike Leach in 2008 and thought we could've landed him back then; didn't think he would seriously be a possibility this time, but I'd be happy to be wrong about that. Leach's age makes him slightly less attractive now than in 2008, but 56 is still pretty reasonable. That conceivably gives him maybe 11 - 15 years if he works out.
I'd still favor Frost or Mullen over Mike Leach, but I'd consider Leach a top-tier hire. Biggest question marks for me:
(*) Can Leach recruit on an SEC level?
(*) Do we have personnel that suits Leach's offense? I'm not sure about that; it could take 4-5 years to see results otherwise; and Vol fans aren't the most patient folks.
(*) Who is Leach going to bring in on the defensive side of the ball? He's had a lot of bad defenses, but he's also never coached anywhere with much in the way of resources compared to the competition.
Regardless, I would be very excited about the hire. He's definitely in the top-tier. He's taken two bottom-tier jobs in P5 conferences and significantly outperformed expectations both times, but (as much as no one wants to hear this), it really took him about 6-7 years to build up the programs (the Butch Jones quote actually does seem to apply to Mike Leach.) Of course, Tennessee also isn't Texas Tech or Washington State.