Texas under Mack would sometimes quit if they got far behind, but I really don't think this was Mack's fault, except possibly when he let the QB controversy (Simms vs Applewhite) go on too long for Texas. Weren't these blowouts kind of unique to playing against OU though? I don't remember Texas folding against teams other than Oklahoma. OU's offense was always high powered under Bobby, with really really good QB's (two Heismans, and one near Heisman) going for us in those years, and some good backs and O-lines too. I think that explained some of those RRS blowouts. Texas otherwise had a stellar defense and could keep the opposing offense contained in those years, and they did it against OU a few times too (like that 16-13 game).
So far my read is that Mack is a better coach than Herman, because this year at least you often see Texas quitting when they're ahead. The fourth quarter seems like no man's land to this Texas team. I looked recently at their box scores, and the following teams outscored Texas in the fourth quarter, some of whom by a lot: Maryland, Tulsa!, KSU, OU, WVU, TT, ISU and KU. That's 8 out of 12, and including all two of the three losses, in which the fourth quarter was when the game was decided.
I'm sincere in saying that this throws me, because one of the things I used to admire about Texas was their ability to come back. I remember all those comebacks under Mack over Oklahoma State for example. Mack had some really impressive Texas teams and such a great run. One of the better coaches I've ever seen. Rivalry aside, I really admire him.