First and foremost, IU and Arizona are both better jobs than the one at Tennessee. Both programs are among the best in college basketball and have a far greater tradition than Tennessee. Additionally both programs are unquestionably the king of their athletic departments, unlike at UT where football and to a lesser extent women's basketball run the roost.
I think Thad Matta leaving XU for OSU is probably the best comparison, though I don't think Xavier was nearly as good of a program then as it is now.
Maybe I'm totally out of touch with reality but I just don't view UT as a plum job.
Xavier has become a really good program, they've got nice facilities and they've gotten to the point where they can compete for high level recruits with schools from the traditional power conferences. I just don't see the need for Mack to consider jumping ship any time a job comes open at a BCS school.