Your point is well taken, but "pretty darn good" is a subjective measure
Clayton was never an all big ten type QB despite having a legit NFL RB, an NFL WR one year (his best season, hands down) and an o-line...well, o-line not so good. But the o-line always improved over the course of the year.
Going back to the Persa thing, I just want to highlight that you are using "Heisman-worthy" subjectively. My research could be "Nobel-worthy" but unless I find myself in Sweden one day, I objectively am not.
I think both you and I agree that Persa had the potential to be an All-American level player (which again, he was not), but was limited by one of two things: 1) the players around him or 2) the scheme. I think it is #2 primarily, where as you think it is #1 (don't want to put words in your mouth).
But Trevor Siemian (a literal NFL start) SUCKED SO BAD at Northwestern and it was not the players around him, those teams had some serious talent (IMO). Thorson also did not play at the level we wanted him to and again, IMO, was limited by scheme. We are frustrated because we think Thorson, a hard working, 6'4" QB with a decent arm and some legs should have been an All-Big Ten player, but he wasn't and someone needs to be blame for that. And frankly, I don't think it's him
I also find it concerning that all of training camp there was word coming from the Eagles camp that Thorson was "raw". How the eff does that happen? How can his QB coach not have done his job in 5 years? There were some similar concerns re: Kafka (I'm an Eagles fan) when he was drafted.
There is a common denominator here and it's McCall.