far as juniors and seniors, they won 9 games and were literally plays from 12+

They had an awkward talent and experience gap after that from a combination of graduations, injuries, and some of those old recruiting classes that weren't panning out.

BYU is the most experienced they've been since then. Loaded with juniors and seniors, and a ton of the sophomores have starting experience.

They'll have a 3 year starter junior at QB. They'll have the most experienced and best OL since who knows when, maybe 08 or so. They'll have juniors and seniors across the board at DL, so both trenches. 4 seniors and 4 juniors across the secondary.

Experience is everything in CFB, especially when you're not a blue blood. Look at USU's big year. Full of seniors and then juniors. Look at Utah last year.
Like the basketball team, the football team wasn't getting old for a few years. Experience will be a big deal this year. Coaches have more of it as well.