Since you mentioned Shapen along with Fant, I did this for a Rumblings question on Thunder and Lightning back in December.
QB1 is 2025 Blake Shapen, QB2 is 2003 Kevin Fant. Both passing QBs with atrocious offensive lines.
The only part I left out because it would have tipped which was which was that Fant had 21 interceptions in 2003 and Shapen only had four last season, which is a pretty stark difference.
I still think a Kevin Fant with a decent offensive line would have been something else. Even as such he was as prolific a passer as we ever had at that point. At the end of the 2003 season, MSU had only had 14 games with a QB over 300 yards, and Fant had numbers 5-8 on that list, more than anybody else at the time.
(Also worth remembering, at the time the single-season record for QB passing yards was 2422 yards in a season by Dave Marler in 1978, and there were only four QBs with over 2000 yards in a season. Some things have changed.)