Yes, theoretically your first paragraph (taking 25 each and every year and redshirting them all) could happen but it rarely does. Sarkisian took 19 guys in the 2009 class (not all his fault but still a 57.89% attrition rate) so he was able to take 31 in 2010. Unfortunately, 13 of those guys washed out (which is a 42% rate) which just too high of a miss rate, especially after 2009. It sure would be great to have a RS-SR RT to step in for Riva and maybe another at SS but instead we have a RS-Frosh at RT and a true soph at SS in Kevin King (who is more of a FS and missed a good chunk of last year with a shoulder injury / surgery after playing for some reason as a lanky true frosh).
The 2012 class is now true Juniors and RS-Sophs but it already has a washout rate of 41%! That also hurts because our depth is being tested at OL (2 washouts from that class in OTs Nathan Dean and Taylor Hindy, who was a panic offer), the secondary (two washouts there in Darien Washington and Cleveland Wallace), and RB (2 washouts in Erich Wilson and Ryan McDaniel).
Talent / depth wise, it makes sense we are now struggling at QB, OL, RB, and the secondary.
-Montana and Derrick Brown were busts as QBs in 2010/2011
-Porter, Kohler, Hindy, and Dean washed out for the OL from the 2010 and 2012 classes. Only grabbed 2 OL in the 2011 class and all that combines as to why we are having to play a RS-Frosh RT a year early.
-RB wouldn't be so bad if Callier hadn't gotten hurt but Erich Wilson, Ryan McDaniel, and Kyle Lewis either never played a down or barely played.
-RS-SR (2010 recruit) Taz Stevenson is Hawaii's leading tackler and he'd be nice to have to compete with true frosh Kevin King, especially with Trevor Walker out now. RS-JR James Sample of the 2011 class played as a true frosh, hurt his shoulder, went the JC route, and now will be starting tonight at safety for #25 Louisville against #1 FSU. He's second on the team in tackles with 3 INTs and 7 passes defended. If he had stuck around, he'd be starting over King for sure and King never would've had to play last year! Evan Zeger also washed out and could've been a back-up SS as a RS-JR. And we wouldn't be starting a true frosh at CB (Sidney Jones) if the former staff had recruited better at CB as both Cleveland Wallace and Darien Washington washed out.
It's simple math ...
If you take 25 guys each year, RS all frosh, and all eligible players stay all 5 years in the program (125 eligible scholarships), the program can absorb an average of 10 people leaving before exhausting their eligibility (assuming 4 years eligible to leave the program - after your RS year, Frosh, Soph, and Junior years).
So while Sark's numbers look bad, it's reasonable enough when you look at taking full classes each year.
The underlying PROBLEM with taking a full class each year is that the overwhelming number of players on your roster are underclassmen. And as we all know, if you really want to win at a high level, your best players in the program should be the guys that have been in the program 3-5 years sprinkled in with a handful of younger players that have the talent to crack into the rotation.
Our defense is a great example of the above. Shelton was probably an above average player through his first 2 years in the program. Last year he started to become a little more consistent and contend on the fringes of being an all-conference performer. This year he will be a 1st team all conference player and in consideration for All Americas in year 4 in the program. Kikaha has had injury issues, but much the same. He's in his 5th year in the program and is absolutely dominating. Shaq was an above average PAC player for most of his first two years. This year he's an absolute difference maker.