I like your optimism. I am probably higher on Jake Retzlaff than you are. I think he is a play maker and will redeem himself from some of the bad mistakes he made last year. I also like the coaches we now have. Time will tell how good the new coaches perform but I am hearing good reports so far.
I do have to question the decision to have ever hired Darrell Funk as OL coach. I'm sure he was a nice guy but when I looked at his resume, I saw that he had bounced around many schools as an OL coach and never stuck around for more than 3 years at any one place. That resume raised a red flag for me and true to form, he lasted 3 years at BYU. ARod gave Funk a ringing endorsement when he was hired. You start to lose credibility when you miss that badly on an important hire. Hopefully, that was a "one off" and won't be repeated with the new staff.
Like you, I am excited to see the new receivers and Hill's defense in year two. I'm expecting BYU to do better than the 4.5 wins Las Vegas predicts.