https://en.wikipedia.org/wiki/Warren_MoonDespite his collegiate success, Warren Moon went undrafted in the National Football League. With no takers in the NFL, he turned to the Canadian Football League. Moon signed with the Edmonton Eskimos, where he and Tom Wilkinson shared signal-calling duties and helped lead the Eskimos to a record five consecutive Grey Cup victories in 1978, 1979, 1980, 1981, and 1982.[12] Moon won the offensive Grey Cup Most Valuable Player award in the 1980 and 1982 games. Moon became the first professional quarterback to pass for 5,000 yards in a season by reaching exactly 5,000 yards in 1982. In his final CFL season of 1983, Moon threw for a league record 5,648 yards, and won the CFL's Most Outstanding Player Award.
He would likely be in 3rd all time in passing yards had he played his entire career in the NFL.
He was one of the best qbs I have ever watched that really doesn't seem to be talked about as much as the others. Even ignoring the CFL stats, just in the NFL alone, had more yards than all time greats like Unitas, Montana and Tarkenton.