If you fill every gap, you are still in a situation where the back is likely 1on1 in any gap he hits. Considering most teams run 1 decent sized lber max, the rb is basically 1on1 with a db sized player in a good 3 gaps. Which is a battle you expect a good rb to win more often than not.
Run schemes today often seek to steal back a body too. That’s why teams run read plays, boot the qb, use jet motion, or what some teams are doing is motioning two guys in jet, then returning one to force defenders to spread out creating seams and gaps inside.
When we pass twice and don’t pa, or semi frequently go empty back field.
If we ran once with Brady, then threw an iso fade to some one like lawler and did that on every single red zone series we would have a drastically higher success rate.
The problem is we often throw twice, don’t threat the run, and don’t throw into the end zone. We throw a screen or short pass and expect the wr to do the rest.