Peyton Manning in after year 7 had just come off arguably the greatest statistical passing season ever, 2004. And was coming off back to back MVPs.
After that, Peyton went on to win 3 more MVPs, and 2 owls, and win 4 AFCCGs
If you could pick either Mahomes entering year 8, or Peyton entering year 8, as your team's starting QB for the next decade+, who are you picking?