In a couple of months Peyton Manning's thunderous 2004 year might indeed take its place alongside the greatest single seasons a quarterback has ever had. First we'll have to see how the rest of the year plays out for him. In the meantime I've compiled a list of the 13 top individual QB seasons in history.

Why 13? Because I wound up with 15 and I absolutely couldn't, but then I had to, cut them to 14, then 13 -- and then I just couldn't go any further. The list is presented chronologically, with rating points based on the modern system, just as a kind of gauge. The rating numbers are no attempt to evaluate these great players, since it was a different game in the old days. The short, controlled pass system of today has lifted the ratings to new heights.

The ball was fatter and less conducive to throwing. Protection was hit or miss, and many passes were launched with the quarterback running for his life. Which makes some of the older performances even more remarkable.

All I can say in defending these choices is that I've seen every one of these players in the flesh, from the wild, open stance, run-and-chuck deliveries of Sammy Baugh to the wonderful, deep touch passes of Sid Luckman, to the controlled, machine-like efficiency with which Otto Graham ran Paul Brown's offense.

Top 13 Seasons Year Player Team  Attempts   Completions   Yards   TDs   INTs   Rating  1943 Sid Luckman Chicago 202 110 2,194 28 12 107.5 Unbelievable boldness throwing the deep pass. He averaged 19 yards per completion and one touchdown every 4.6 passes, a figure never surpassed. In the championship victory over Washington he threw five TD passes and intercepted two himself. Yes, the QBs played defense in those days. 1945 Sammy Baugh Washington 182 108 1,669 11 4 109.9 The overall league completion percentage was 45.6, and seven of its top passers were below 40 percent. Yet Baugh posted an unheard of completion rate of 70.3, a record that lasted 37 years as the top mark and still ranks No. 2 all time. 1947 Otto Graham Cleveland (AAFC) 269 163 2,753 25 11 109.2 Like a breath of fresh air, Graham arrived as the front man of a new league and a radical system that featured cup blocking for the passer, precise, timed throws to the ends and, oddest of all, a coach who called the plays himself. 1959 John Unitas Baltimore 367 193 2,899 32 14 92.0 The great sudden death victory over the Giants in the 1958 championship was just a memory when Unitas, the toughest QB in the game, put together another magnificent season that ended with 31-16 victory over the same foe. This was Unitas at his best, at the peak of his game. 1959 Norm Van Brocklin Philadelphia 284 153 2,471 24 17 86.5 The Dutchman broke in with an L.A. Rams system that set many offensive records and sent not one but two QBs to the Hall of Fame, Van Brocklin and Bob Waterfield. He was always a great gunslinger but the culmination of his career came at age 34, when his deep strikes and bold approach brought the Eagles a championship. 1969 Greg Cook Cincinnati 197 104 1,854 18 11 88.3 Bill Walsh, his offensive coach, says that the league never has seen a rookie like this 6-4 flamethrower. He was the most feared passer in the game. His completions averaged 17.5 yards and no one has come close to that number since then. Three tight ends on that bombs-away offense of Walsh's averaged better than 20 yards a catch. A shoulder injury ended Cook's career after his one remarkable season, and with him went Walsh's dreams of creating the greatest down-the-field attack in history. 1984 Dan Marino Miami 564 362 5,084 48 17 108.9 In his second season he set a record for TD passes that most people agreed never would be broken, except possibly by Dan himself. 1989 Joe Montana San Francisco 396 271 3,521 26 8 112.8 Still on the comeback trail after a shaky period in his career -- bad back, squabbles with his coach -- Montana put a lid on his troubles with the highest QB rating ever compiled up to then. The season culminated with his five TD passes against Denver in the Super Bowl. 1994 Steve Young San Francisco 461 324 3,969 35 10 112.8 Young understudied for four years under Montana. Four years after he moved in as the starter he inched ahead of Montana's record rating, and now both Niners, who rank one and two all time, wait to see if Peyton Manning will capture the title. 1996 Brett Favre Green Bay 543 325 3,899 39 13 95.9 Take your pick -- 1995 or '96, both Super Bowl seasons and his two best statistical years. His numbers were slightly higher in '95, but '96 was the year in which the Packers won it all. 1997 John Elway Denver 502 280 3,635 27 11 87.5 He had better statistical years -- in fact his best one came in '98, his farewell season -- but fourth-quarter comebacks were Elway's game, and he had four of them in '97. At age 37 he still hadn't lost the magic. The final late comeback, and the 45th of his career, came in the Broncos' first Super Bowl victory at the end of this season. 1998 Randall Cunningham Minnesota 425 259 3,704 34 10 106.0 There was no logical reason why Cunningham should have the breakout year of his career after being cut by the Eagles, staying out for a year and then riding the bench for another season. But in '98 it all came together for him as he led the Vikings to a 15-1 record, tied for the best in history over a 16-game season. 1999 Kurt Warner St. Louis 499 325 4,353 41 13 109.2 The Greatest Show on Turf, with Warner, an escapee from the Arena League, as its ringmaster. Trent Green got hurt, Warner got his chance and the result was the fifth highest rating in history.  React: Greatest season ever by an NFL quarterback? Your name: Your E-mail Address: Your Hometown: Your comments:

Sports Illustrated senior writer Paul Zimmerman covers the NFL for the magazine and SI.com. His Power Rankings, "Inside Football" column and Mailbag appear weekly on SI.com.