You obviously learn the most when you play better competition. Having played a team like Ole Miss, BYU now has a better idea of what it takes to beat teams like this. I'm confident BYU has the talent, but they are young, overall, with a new coaching staff as well. They are learning with each game, but this game will accelerate the learning process due to the improved competition.
It's not uncommon at all to see teams take some lumps early in pre-season and even conference play, but then keep improving and peak toward the end of the season and then excel when it's time for conference and NCAA tournament time.
Hopefully, that will be the case for BYU.