I don't have it now, but there was an article once that chronicled Luke's health from highschool through college. It was almost shocking. Its hard to imagine being capable of such elite athletic performance, but also have constant, recurring, surgical, issues.
I suppose BYU could have managed his health better. But his health history leads me to believe that his career was in constant peril as long as he was playing football.
And managing a player is a double edged sword. Without the carries, yards, and heroics, Luke doesn't produce enough to get drafted (hypothetically). Particularly at Running Back. IMO, it is folly to want your kid to play QB, followed by RB. QB is roulette, because only one guy per year is likely to play. RB is wild because even NFL teams don't carry many, and careers are very short.
Then again, there is no "easy" position.