Football is a different sport than most because system 100% matters. If you are in the wrong system (look at KVN at Detroit vs NE), talent won't matter.
There are too many players on the field and too many assignments.
A first round pick gets between 10-20 million guaranteed. A third round pick gets...what? $300,000 guaranteed?
That is a HUGE difference.
If you are a kid and one school will highlight you and make you shine in their system vs another school where you will be a great player, but not shine as brightly...and that drops you to the third round...
Well, you just lost 10-18 million dollars.
As much as you love BYU, it ain't worth that risk.