Identifying these other QBs is proving challenging, CA. Changing it to percentage of years in the top 5 (with qualifying attempts) has made it infinitely more difficult, and I'm trying to look at this from every possible perspective to find the answers. One starts to see things they didn't before. Quarterback A, at first, I thought of as several steps below Rodgers and Montana, simply because of their average QB rating finish. But when I look now, and see they finished top 5 in 31.3%, and the other finishes being 25%, or 12.5%, these are all factors of 8. 1/8 is 12.5%, and 2/8 is 25%. So, QB A threw enough passes in 16 seasons to qualify for the league leadership. That means they finished top 5 in the NFL in QB rating 5 times, as 5 of 16 is 31.3% (31.25% rounded). Finishing five times in the top 5 in passer rating is actually pretty damned good. That average finish could easily be skewed by a few rough seasons at the start of his career, and another one or two at the end. But that peak...would be Pro Bowl-caliber for at least half a decade.
My head is swimming. 