I'd like to see more of the following:
sprinters -> CB
CB -> S
S -> LB
LB -> DE
DE -> DT
DT -> OG
tall (6'3"+) WR -> TE
short (5'8" to 6'0") WR -> RB
TE -> OT
OT -> OG
I don't think everyone should move this way, or even most players, but I think a 5-15 total players per year could be a way to improve athleticism across the board.