Coaches who are "smart" dont spend their precious precious practice time "tackling" and "blocking". They spend it mentally, on formation shifts and talking...and talking...and talking. To the point the players are so worried/thinking about every footstep, hand placement, strongside/weakside, right leg/left hand...that they forget to run/hit/tackle/block/smash/catch/compete.
Going from good high school to big time college ball takes months of coaching and new technique. We all know that. But why, for the love of God, when u only get 20 hrs per week in season; please do the basics of football 101. Teach in the film room, unleash the beasts on the field. Tackle, block, run, catch, compete.
If a majority of time is spent on "mental reps", you're done. Get physical, get nasty, let em play.