There may be a few players who are so established and elite they can say "Hey, I don't need to be on the field to show that I am NFL worthy. I'll stay out to stay healthy, that's my ticket to the NFL." There are players, too, that know they aren't headed to the NFL and don't want to take unnecessary risks with their health.
But for almost every player, they know they have to be on the field to prove their worth.
This doesn't mean that BYU couldn't/can't be better about player management. I am pretty skeptical of a player who says he was given the ball too often, and blames a short career on "overuse."
Strange analogy. Gun Control Advocates often want to restrict or eliminate specific characteristics of guns. But the really important characteristic of a gun is that it fires chunks of lead at super high-speeds. Everything else is relatively meaningless. Kind of similarly, the dangerous part of football is . . . football. Safer football is a noble goal. But injury-free football is an oxymoron.