It's only a secondary factor. There are many examples of first round picks that weren't particularly great in college, but the NFL valued their skill set higher. Josh Allen is a perfect example.
As BYU fans, we want to see a QB lead the team to wins. NFL preparation is an after thought as fans.
On the other hand, BYU is way behind in NFL development, so it helps the program if a player succeeds in the NFL even if they were inconsistent at BYU.