It's easy for fans to blame the o-line, running game or WR's on poor QB play, but in the end a good QB takes the good with the bad and produces.
Stanzi had a significant drop in TD:INT ratio in the last two months of the season from the first half. 19:2 to 6:4. I don't care how you paint it, that's not all on the running game.
Stanzi's stats were noticeably worse in close games. When the final margin was 0 - 7 points he was 59.2%, 12TD, 5INT and took 14 sacks. When the margin was greater, he was approx. 71%, 13TD, 1INT and took 5 sacks.
When Stanzi was winning he was 65 - 73% completion rating. When he was losing he was 50 - 57%.
Stats are a funny thing, because they can be viewed multiple ways, and while he put up some good numbers this season, and throughout his career, there are stats to suggest that he did indeed struggle as a closer. In fact, arguably his inability to close was what kept us from having a great year. Outside of Indiana, who shouldn't have been a contest and Mizzou, who we had time to prepare for, he didn't win a close game all year.
That's a very critical component of a successful QB at any level. QB's with worse stats that can close and find a way to win are historically more highly regarded. Stanzi will have to be better than that at the next level to have any chance to survive in the league.