Be Better
If you're going to use passer rating as your standard, then David Ash's 2012 and 2013 seasons were better than Chance Mock
David Ash 2012: 153.3
Case McCoy 2012: 169.0 (242 less pass attempts than Ash)
David Ash 2013: 156.3
Chance Mock 2003: 148.74 (135 less pass attempts than 2012 Ash)
Do we need to compare supporting casts that both played with? Ash played with Mike Davis, Marquise Goodwin, and Jonathon Gray. Mock had the Big 3 at WR as seniors, sophomore Cedric Benson and sophomore David Thomas at TE.
Mock's "high" passer rating is the result of a very small sample size as a redshirt junior. He was not pressed into action as a true freshman, like Ash or redshirt freshman, otherwise his passer rating would be a lot worse. Against, NMSU, Tulsa, Rice, and Baylor, Mock competed 66.67% of his passes. Against the rest of the opponents, he completed 49.6%.
My hunch is your inclusion of Mock is tied to some sort of personal connection/anecdote/experience with him that you're not disclosing.