Decision-making
Recognition of defenses

Things that coaching can't improve (at least much):

Athleticism
Arm strength
Mobility
Heart

Every QB has deficiencies. I lived through BYU QB's who lacked the arm strength to be great (Feterick, Riley Nelson). I lived through immobile QB's (John Walsh, Tanner Mangum). I lived through BYU QB's who lacked the heart and/or drive.

The things Retzlaff needs to improve are all things that can be improved with coaching and experience, and they're things he's already shown he can improve in.

According to some here, all he needs to do is throw two fewer red zone interceptions next year than he did this year. Because he didn't throw interceptions at a particularly high rate overall, when compared to past BYU QB's. And he's shown as much heart and leadership as any BYU QB since Detmer.

You don't start over from scratch on a team returning so many players from an 11-2 season, with a QB who hasn't been in the system for two years already. Maybe he hasn't shown as much in that system as many here would like as quickly as they would like, but it doesn't mean he won't get there next season.

I love his fire, his athleticism, his leadership, his confidence, and his raw arm talent. A full offseason in the system, getting all the offseason and preseason work as the starter is going to pay off next year in an improved efficiency and familiarity with the offense.

It would be absurd to toss away what we have in Jake, for some unknown, new and/or raw QB talent who is at least two years behind him in knowing the offense.