If he does not improve even the players he had last year from year 1 to year 2... then he probably isn't "the guy".
The "guy" is the coach who has the coaching talent to turn it around and catches some breaks as well. I feel better about Pruitt's chances than I ever did Jones'. He's a coach... not a used car salesman.
I'll use Jones as an illustration. The best OL he had was the one he inherited from Chaney, Pittman, and Dooley. Rumors at the time were that they basically ignored the "technique" coaching Jones prescribed. The OL was much worse in the following year and people said "give him time he's purging Dooley". In years 3 and 4... not much better but Dobbs made lots of things look better than they were. Year 5 then this past season, we saw the real product of Jones' OL recruiting and development.
I would be shocked if UT has a dominant OL this fall. But they should be noticeably better even if the last starting 5 are the starting 5 for BYU. If Pruitt has hired the right S&C staff then they'll be bigger and stronger. They'll have a whole season of experience, a spring of corrections, a summer of film review, and a pre-season camp to become as sharp as they can. That is A LOT of opportunity to make those guys better.