Competition almost never matters. When a guy is good you just know. Rapp played against a bunch of small unathletic white dudes but you could tell he was a baller.
That's not true with QB, RB, and MLB. The speed of the game is critical in developing those positions.
Burmeister for instance was the most accomplished QB in the history of the San Diego area, but he played small schools with shit players and a year he looks like a fucking combine in coming at him at 75mph on every step.
The state of Oregon hasn't produced a good ball carrier in my lifetime outside of Tyner and it took him three years for the reasons listed before. Nall isn't good.
You play a certain way your whole life and it's what you know and the next year it isn't even close to what you need to be good. That doesn't cure itself overnight.