I would take Gruden's evaluations with a grain of salt, here's what he said about Nathan Peterman before the draft
Before the draft, Gruden wrote
extensively on why he thought Peterman was the most pro-ready quarterback in the 2017 class.
"Peterman is ready to walk in and be a contributor from day one," Gruden wrote on ESPN.com in April. "He just looks like a pro quarterback -- coming out of the huddle, running an offense with different formations, shifting, motioning, different patterns that other colleges don't run. Peterman will recognize route combinations and associate formations." "He is sharp. He is in the channel, I think, of success. I think he's going to be a real good pro quarterback,"
Yes he picked Peterman as the most pro-ready above Trubisky, Watson and Mahomes.
So if it would have been a 4 horse race, not only did his horse come in last, it had to be shot and put down.