I don't think Kentucky is unbeatable by any stretch of the imagination but I also don't take much from those regular season "close calls," beyond the fact that everybody was gunning for them every night and they never lost, despite probably not treating every game like a super bowl like their opponents did. I think it's a little different now, we we saw then they were motivated to beat WVU.
That being said, I think AZ has the best shot at them, mostly because they have decent size (although Tarczewski is an enigma to me, great one minute, non-existent the next) and they seem pretty tough-minded and resilient. I love Rondae Hollis-Jefferson.