4. Warren Moon (underrated)
Warren Moon’s numbers are lower than you might expect for a quarterback with his reputation, but that’s because he spent the first six years of his career in the Canadian Football League. He didn’t come to the Houston Oilers until he was 28.
His late start in the NFL didn’t hold him back, and in fact, maybe helped him as he played until was in his 40s. At age 41, Moon threw for an NFL leading 245 yards per game. Let’s see Brady do that. Moon ranks 5th all-time in passing yards in the NFL, but if you add in his Canadian numbers he ranks second. Incredible.