People just underestimated him because he went to Wyoming and didn’t put up crazy numbers. But, he had the physical traits, the arm talent, the athleticism, and, most importantly the mental makeup (leader, IQ) to be a very good QB, he just needed to work on some things to get it to all come together.
Especially with QBs, I think some guys (example Tua, Darnold, Haskins) come out of college over hyped because they played on really good college teams and this inflated their stock. Don’t overlook the guy from the little school.