for decades.....
It's really an unfortunate phenomenon that has been happening at BYU quite frequently, especially at QB.
A QB has a very promising season with a lot of potential for the future....and it's like they psyche themselves out and start putting a lot of pressure on themselves but in a really weird overconfident way....they lose that "eye of the tiger" combined with the "just go out and play loose and easy" the following seasons.
Max Hall was one of the only BYU QB's where that didn't happen to them, but almost everyone else? It's tragic.
And you are right, it's definitely a mental issue. BYU as a program has had a problem with mental toughness for a very long time. I don't know if it's the mission or what, but I am routinely concerned about BYU's mental stability and state.
KW on the other hand seems to have that part of the game absolutely DOWN.