True 9 man rotations aren't going to happen. The minutes just aren't there and if you don't believe me go back through FSU's games, in particular the games that were closer or their losses (more on this in a sec). They may have had 9 or even 10 players they felt comfortable going to, but they usually had 8 man rotations and sometimes less. The reality is while players want to play, that's not just true of young players. Starters want to play big time minutes. It's a balancing act and 9 and 10 man rotations just aren't going to be sustainable.
IMO people greatly overexaggerate what the get old stay old philosophy means. It doesn't mean always having 3 seniors or 5 upperclassmen. It means consistently having a core of uperclassmen to lean on. Sometimes that may just be 3 starters and the rest of the rotation is sophs and freshman. But if those 3 upperclassmen are playing 30+ minutes, then you are still old, at least as far as the philosophy goes. And you can maintain that even with a 7 man rotation.
The reality though is that Pastner is doing a big rebuilding job. Yes, even in year 5 there are still aspects that he is building up. One of those is the fact that winning begets winning and that is especially true of depth. For two major reasons, at least, that I can see. One is that it's a lot easier to look like a deep team when you win every other game by 15+. You can play 7 or 8 in more competitive games and then go 9-10 in games you are in no danger of losing after the half. This year we rarely had those opportunities, and after the start of the year the staff was probably gun shy about going deeper in the bench early (especially with Meka and Maxwell being hurt). The second, and the one that is just starting to be a factor for us hopefully, is that it's a lot easier to convince players to have development years where they don't play big roles if they believe they will be competing for championships when their time comes. That's even more true if you can bring in players when they expect that to be the case so they aren't shocked or as likely to be frustrated with low minutes.
Building on your point. As you get deeper into the season and play more talented teams the rotation almost always tightens. Just part of the game.
All 4 of the teams in the Final Four are basically 7 to 8 man rotations. Once you get into conference play you simply are not going to find many teams willing to go deeper than that because the dropoff at that point becomes too great and other teams can take advantage of it.
Gonzaga has had 1 game all year decided by less than 10 pts and yet you look at their rotation and it's basically a 7 man rotation: 31.2, 30.9, 29.2, 28.5, 27.6, 19.4, 13.6. Then they have some deep reserves that get 5-7 mpg because they win so many games going away.
Baylor may have the deepest rotation and it is eight - 34.8, 33.0, 31.9, 26, 22.5, 20, 15.1, 13.9. They basically have a big 3 and then the others fill in around them.
Houston also goes 8 deep - 35.8, 33.5, 27, 26.3, 19.3, 19.3, 15.5, 15.0
Finally UCLA, like Gonzaga, is a pretty short bench team, in the NCAA it is 39.8, 37, 34.8, 31.2, 24, 14.1, 9.9, 7.4
Most NCAA teams are pretty similar, you are going to have a core group of 2-4 guys that play 30+ min and then another 3-4 that play 13-25 min. I'd love for our bench to be strong enough that we could comfortably reduce the big 3's time to 33-35 mpg if they all return. FWIW, here were GT's min in ACC games - 37.4 (Jose), 35.7 (Moses), 34.9 (Devoe), 30.1 (Usher), 25.6 (Bubba), 23.6 (Moore), 10.9 (Kyle),
6.4 (Rodney, 12 games).