It’s just a numbers game. By default there would be a few players who slip through any which way. Kelly, Marino, Elway could probably play today, I’m sure there’s others too.
And does Stafford or Goff have great mobility? Or Brady or Manning?
Kelly was 6’3 220lbs in his prime, which is ideal height with a very good arm.. Had the heart of a lion with great mental faculties. How is he not a top 10 QB at the very least?
More so the moxie of Baker Mayfield and not the talent level. Kelly is a few levels ahead as far as talent goes but they both have/had that grit and swag.