Natural maturation and an elite S&C coach make huge differences as a player progresses. I think part of USU's success has been due to our S&C program and the fact that many of our players are a bit older and more mature due to Mormon missions. Players are generally a bit more mature and hardworking and that creates a culture where the only thing that's acceptable is working your tail off.
How do you define success? Do you look at record alone without accounting for quality of opponent? There is no denying that USU is winning ball games. There is also no denying that USU doesn't beat teams who recruit in the top 79 teams. The devil is in those details.
Would you take an undefeated high school team over an SEC team with a losing record (top 50 recruiting in division 1 cfb)? If no, you realize the dearth in talent is fatal and therefore records aren't necessarily indicative of quality.