When he demonstrates that he can go all out day after day, game after game, then we can start to breathe easier. Even at that point, there will be a considerable tail of concern about his knee health; which is why i have downgraded him to a late first round draft choice.
One thing that is not a concern, and perhaps just a CBer myth, is that shooting guards must shoot 3s well in order to get drafted in the NBA. Just don't see that in the data. It would be foolish for coaches to permit KC to fire up a hundred 3s next year even if he improves that skill given potential 40% 3 point shooters Fischer, Haws, Winder, Neilson, Nixon, and Toolson . KC is brilliant at taking the ball to the rim and that gift is what gets players drafted. Fortunately, that is also what BYU will need from him next season, i.e. what the coaches absolutely want from him!
BYU will have at least six excellent 3 point shooters next season, but only one guard who is brilliant at driving to the basket.