You're missing the most important aspect that the Bills discovered when scouting him.
He had the raw talent at Wyoming to make throws on pure instinct
that Elway and Marino would never have been able to make. There's tape of him making 1 of 1 throws.
NFL scouts can keep looking for the next Josh Allen, a guy with high athletic upside and a huge arm all they want. But if he doesn't have the same level of raw arm talent, and by that I mean the ability to make elite NFL level throws, they are going to fail.
He was inconsistent hitting the easy throws, not bc he was an innaccurate QB. But bc he hadn't been taught proper mechanics. And he certainly needed to learn how to read defense, and accept taking the give me throws.