That's pretty much it defensively. He actually ends up guarding the 2 a lot in college as well because a lot of 2's are spot up shooters and don't have much driving ability at that level, and Jackson Emery ends up sticking the 1. To be a starter in the NBA he certainly would need to put up big offensive numbers to cover for his lack of defense.
Perhaps because he is so important to BYU on the offensive side they smartly dont want him to kill himself on defense. So maybe then in the NBA he will be able to concentrate more on defense. Not trying to say he will be a good defender, but adequate like Nash.