Jarrett Stidham from Auburn is the guy I think has a huge upside.
Could have been an early pick last year, but returned for another year of polish and experience. He is a junior and will be coming out this year. Nice size 6ft 3in. 215 pounds.
Stidham has a strong arm, efficient, and a mobile quarterback. He lead Auburn to the SEC championship game last season.

Chris Petersen currently the head coach at the University of Washington, is a coach that may be a replacement for Vance Joseph. He put Boise state on the map before taking the job with Washington. I would also consider John Harbaugh who would immediately bring some stability, and competence, to Denver could also be a candidate.

The coaching carousel has begun and it should be interesting to see who stays and who gets the boot.