Another look at this:

How many players from each year's recruiting class out of HS (so players that CAN play 4 years straight - so this would include Taysom Hill)?

Note: Starters are players listed first on the depth chart. I didn't include KR or PR in the ST starter list. Also, there are 12 starters on offense b/c BYU lists 3 WR, 1 TE and 2 RB slots. You can see a pattern below. If there were no medical RS or grey shirts, 2011 would be the only year with all four classes represented. It would go down from there to the SRs from 2008 and to the FR of 2014. Only at BYU.

We still get big benefits from the 2010 class. People focus on the busts from that class but it still is having a HUGE positive impact on BYU's roster.

2007: 1 player left (1 on two-deep - 1 starter) - covers only 1 class (SR)
2008: 4 players (2 on two-deep - 0 starters) - covers only 1 class (SR)
2009: 6 players (6 on two-deep - 5 starters) - covers 3 classes (SR, JR and SO)
2010: 15 players (10 on two-deep - 6 starters) - covers 4 classes (SR, JR, SO and FR)
2011: 9 players (3 on two-deep - 2 starters) - could cover all 4 classes but there were no 4-year players that stayed from that class
2012: 7 players (3 on two-deep - 1 starter) - covers 3 classes (JR, SO and FR)
2013: 6 players (6 on two-deep - 2 starters) - covers 2 classes (SO and FR)
2014: 8 players (2 on two-deep - 0 starters) - covers only 1 class (FR)

Total: 56 players (33 on two-deep - 17 starters, including all 3 ST starters)

Transfers/Walk-ons: 53 players (18 on two-deep - 9 starters)

Seniors: 19 on two-deep and 12 starters - 4 on offense, 5 on defense (3 of the 4 in the secondary) and 3 on ST
Juniors: 12 on two-deep and 9 starters - 5 on offense, 4 on defense
Sophomores: 12 on two-deep and 4 starters - 2 on offense, 2 on defense
Freshman: 7 on two-deep and 1 starter - 1 on offense