Being a UT fan for over 50 years, I will say that Mack did some really positive things here despite the fact he overstayed his welcome/
1) He totally flipped the recruiting on aggy eventually getting RC Slocum fired and getting Texas back to its rightful spot as the prominent program in the State. I remember in the mid 1980, a prominent sportswriter for the DMN(later at the FWST) wrote that aggyy will forever be the prominent program in Texas at that point and it's just wishful thinking for UT fans to ever think we ever get it back/ Mack turned that little prophecy wrong and that same sportswriter started calling him "Macky Mack" as a result.
2)He proved that Texas can be a constant 10 game winning a year program again. That all our wins and championships were not just a result of carpet bombing on recruiting. UT was accused of recruiting players just to keep them from playing against us. BTW, it's not true at all. The common thought among sportswriters was that scholarship limits had exposed our football program as being a fraud on the national scene Mack proved that theory totally wrong.
3) He totally embraced and respected the UT tradition unlike the previous coach before him. He wasn't aiming to just be good once out every five years like Mackovic was. Mack wanted to put the program in a place where it was nationally relevant every year.
True,. he eventually got lazy, did not make the necessary changes on the offensive side of the ball but he did do some good things while here. This UT fan is appreciative of it.