It's hard to rank great players in pro football because there are so many fluctuations in pro football history, making it extremely difficult to compare players across different eras. In my rankings, I try to deal with this by considering how dominant each player was for their era, what contributions they may have made to the game to help it evolve, and how productive they were given the circumstances they had.
Note a couple of implications of this approach. First, winning is important, but I consider winning within the context of the team each player was on. Second, I look at statistics based on the era in which they were compiled; quaterbacks playing since 1978 have, of course, enjoyed a huge advantage over their predecessors because of rules changes, but that doesn't mean they were better.
Ok, enough talk. Here's my list, with brief explanations.
The Elite Five - if there were a Mount Rushmore of Quarterbacks, and we allowed for five heads, these would be the men represented.
1. Sammie Baugh - Simply put, he invented the position. Before he came along, QB was a kind of hybrid position, involving mostly running. He was dominant for his era - he once completed over 70% of his passes at a time when completed under 40% was commonplace for a starting quarterback, and league-wide averages were usually under 45%.
2. Johnny Unitas - Probably the best pure passer ever, given the competition and the rules of the game. Unitas played at a time when defenses could punish passers with few restrictions. Elbows to the head, late hits, diving at knees -- all this stuff was routine. He also played at a time when the game was developing a complexity that was challenging for many quaterbacks, and Unitas had to be an offensive coordinator on the field, calling plays and then executing them.
3. Dan Marino - This is probably my most controversial pick, so let me defend it here. Many others would argue that Marino wasn't even the best among his contemporaries -- that Montan or even Elway were better -- and they'd base their selections on championships won. Marino, though, didn't play with very much talent around him. His Dolphins teams typically had terrible defenses and no running games to speak of. Even his celebrated receivers were, I would argue, actually average players who put up huge numbers BECAUSE of Marino. Duper and Clayton were fine players, but nothing special. Marino stepped on the field as a rookie, and quickly began eating defenses alive. In his second season, he demolished long-standing NFL records, including the record for TD passes, which he beat by 25%. Montana and Elway were great; no argument here. But Marino was better.
4. Otto Graham - A productive winner who led great teams to championship after championship. I don't put as much stock in his AAFC success, but he played in the NFL for six years and the Browns played in the NFL title game each time. When he retired, the team went downhill immediately, which suggests the void he left behind.
5. Joe Montana - The perfect passer to take advantage of the 1978 rules changes, Montana invented the kind of quarterbacking that's most successful today - one based on mobility, smart reads, patience, and accuracy. He was clutch, though not quite as clutch as some remember - he had a few awful playoff games, and the winning TD pass to John Taylor in Super Bowl XXIII came right after throwing one into the chest of a Bengal, which was dropped. Still, a brilliant, very tough, and extremely accurate player. In 1987, '89, and '90, he led a nearly unstoppable offense.
The Second Tier
6. John Elway - It seems counterintuitive that three guys from the 1980s would represent half of the top six, but there you go. It's hard for me to think of a player who was better than Elway outside of the ones named so far. As elite an athlete as ever played the position, Elway did things that no other passer could do, and he carried some very poor offenses to three AFC titles in four years before he even knew what he was doing. Granted, he had a few down years, but so did everyone on this list. The fact that he played at a high level very late in his career testifies to his overall talent.
7. Terry Bradshaw - Not a consistently great player throughout his career, and a guy who benefited from amazing talent around him, but still: the rings don't lie. Won four titles in six years, coming close to winning five of six. That's a stretch during which he made big clutch play after big clutch play, big game after big game. The Steelers, for all their talent, had to fight through a lot of close games to win some of these titles,including tough regular season brawls with tough divisional opponents and playoff runs where they had to fight off mini-dynasties, like the Cowboys, Raiders, Dolphins, and Vikings. So successful were his teams that they effectively wiped their divisional foes from memory, having prevented them from ever getting anywhere. Keep in mind that in 1975, he led the Steelers to a 12-2 record when the Bengals and Oilers each posted 11-3 records.
8. Y. A. Tittle - Ranking Tittle ahead of championship players like Starr, Manning, Staubach, Young, Moon, Favre - what? Yes, I am. Like Unitas, Tittle played during an extremely violent era when the rules were not kind to passers, and he put up numbers that were far above average. That he won no championships was hardly his fault.
9. Roger Staubach - A great all-around player. Played during the brutal 1970s, when astro turf combined with favorable defensive rules to make life very painful for quarterbacks. Clutch, consistent, and charismatic, Staubach was a tremendous player, and would have been, in any era.
10. Bart Starr - He did play with a great team around him, but, like Bradshaw, those championships would not have been won without a great passer to complete clutch third down after clutch third down in big game after big game.
THIRD TIER
11. Sid Luckman - An old timer who perfected the style of quarterbacking that died with the 1940s, a style that depended on a passer who could run between the tackles like a running back, punt on the occassional third down for field position, display some slight of hand in the single-wing, and play some defense to boot.
12. Tom Brady - Has put together a better record of acheivement than his contemporary, Peyton Manning, with less talent. I rank him this low simply because I think those passers who have played most of their careers after 1990 benefit from rules that make playing quarterback relatively easy, compared with their ancestors.
13. Fran Tarkenton - Invented an entirely new style of quarterbacking, one that featured mobility, not just to evade the rush, but to create new passing lanes and new types of pass plays. Very accurate for his era, and the most important player on an excellent team.
14. Brett Favre - In an era of over-coaching, when players like Manning and Brady play a somewhat pre-programmed and robotic style, Favre has been a bit of throwback, with his improvisational, river-boat gambling approach to the game.
15. Sonny Jurgensen - Has gone unrecognized because he spent most of his career on terrible teams, but one of the best natural arms in football history.
16. Steve Young - Very accurate, mobile, tough, smart, and productive. Given the talent around him, should have probably won more championships, which is why I rank him as low as this.
17. Norm Van Brocklin - Explosive playmaker from the 1950s.
18. Peyton Manning - So consistently great that he's almost easy to forget. Ho, hum, another year, another 4000 yards from Manning. I rank him a bit lower than most, because: his great numbers have been achieved in a passer-friendly era; he's put up a lot of huge numbers against some terrible teams; has a poor playoff record; has played with excellent offensive talent around him.