The greatest QB season ever? 2013 may not even be best of Peyton Manning's career

Peyton Manning threw an NFL-record 55 touchdowns in 2013. (John Leyba/The Denver Post via Getty Images)

Recent bias, knee-jerk reactions and hot-sports takes cloud the discussion surrounding Peyton Manning's historic 2013 season. The Broncos' future Hall of Fame quarterback smashed the NFL record for touchdowns and holds the single-season passing yards record, barring a reported league review of a throw in the last game of the regular season.

But how great was Manning this year? Where does his year rank in terms of the greatest season ever by a quarterback?

The answer seems obvious: it was the best ever. Look at the stats. But the numbers may mislead you.

Consider the following: In 1984, Dan Marino set the NFL record for single-season touchdowns with 48. It took 20 years for Peyton Manning to break that record, with Manning tossing 49 as a member of the Colts in 2004. Just three years later, Tom Brady broke Manning's record, throwing 50 in 2007. Now, six years later Manning has the record once again.

After Week 17, when asked about the record, Manning quipped that Brady would probably just break his record again next year.

He might. And that's part of the problem with trying to put this season into perspective; we've reached a new normal in terms of passing. When Drew Brees set the passing yardage mark in 2011, three other quarterbacks threw for 5,000 or more yards. If Aaron Rodgers had played in Week 17, he likely would have been the fourth (Rodgers passed for 4,643 yards and sat out Week 16 with the Packers sitting 14-1).

In the last six seasons, the touchdown and yardage marks have been broken twice each. The single-season completion percentage mark --nearly 30 years old -- was toppled (Drew Brees posted a 71.2 completion percentage in 2011), as was the passer rating record (Aaron Rodgers finished with a 122.5 QB rating in 2011). And Philip Rivers had a shot at the percentage record most of this season.

Here's a look at the four most recent record-breaking seasons side by side.

Player (Year)	Completions / Attempts	Completion %	Yards	Yards per Attempt	TDs	INTs	Rating
Tom Brady (2007)	398/578	68.9	4806	8.3	50	8	117.2
Drew Brees (2011)	468/657	71.2	5476	8.3	46	14	110.6
Aaron Rodgers (2011)	343/502	68.3	4643	9.2	45	6	122.5
Peyton Manning (2013)	450/659	68.3	5477	8.3	55	10	115.1

Manning's sheer production, in the lens of the current season, seemed overwhelming. Compared to these recent record-breaking seasons, Manning's numbers aren't all that special.

Manning and Brees attempted nearly the same amount of throws and finished with essentially identical yardage totals. Had Brady thrown the ball as often as Manning, his touchdown pace would have exceeded that of Manning's. And Peyton's efficiency is second-lowest as measured by passer rating.

In fact, 2013 may not even be the best Peyton Manning season ever. That distinction must go to 2004, at least statistically speaking.

Player (Year)	Completions / Attempts	Completion %	Yards	Yards per Attempt	TDs	INTs	Rating
Peyton Manning (2013)	450/659	68.3	5477	8.3	55	10	115.1
Peyton Manning (2004)	336/497	67.6	4557	9.2	46	10	121.1

Together, Manning has put together two of the best seasons of the last generation, but it's hard not to notice the difference in efficiency -- specifically that the 2004 version of Manning was much better on a per-play basis. In fact, had Manning maintained his per-attempt average from '04 in '13, he'd have topped 6,000 yards. The gross stats like yards and touchdowns are a direct result of Manning tossing it 162 more times this season than in 2004 -- the equivalent to an extra five games based on his 2004 averages.

Therein lies the rub: Teams are passing more than ever in a league tailoring rules to benefit offensive players, particularly quarterbacks. To wit, Brady has had two rules created essentially for plays he's been involved in.

Aggregate stats have always been misleading, but it seems we're slowly figuring out how to parse them

It's why Aaron Rodgers, in a season in which Drew Brees finished with better gross numbers, was the MVP: he had the most efficient season in modern NFL history.

Manning's 2004 season was tops in this group in terms of touchdown percentage (the number of touchdowns based on total attempts) and his season is probably the only one capable of standing up to Rodgers in 2011 by efficiency standards.

Not surprisingly, the two worst figures in that regard are Brees in 2011 and Manning this season; both threw the ball significantly more than their peers.

The more you throw, the bigger the numbers grow, inflating the same way baseball statistics did in the steroids era. Only it would be like if baseball suddenly had six plate appearances per game instead of four.

It's why baseball gurus developed statistics like Wins Above Replacement (WAR), and other combination stats like OPS+ and average on balls in play. Traditional metrics simply come up short when comparing players side-by-side.

Football Outsiders has developed several football metrics to help us reconcile this issue, particularly in the face of a sport where so-called advanced metrics are difficult to come by.

For quarterbacks, they have three statistics we can use, DYAR, DVOA and Effective Yards. DYAR is yards above replacement adjusting for opposing defenses, while DVOA is the same but on a per-play basis. Effective Yards translates DVOA into yards per attempt metric and accounts for total usage.

Player (Year)	DYAR	DVOA	Effective Yards
Peyton Manning (2004)	2434	58.9%	6109
Tom Brady (2007)	2674	54.1%	6946
Drew Brees (2011)	2259	38.3%	6763
Aaron Rodgers (2011)	2121	48.4%	5671
Peyton Manning (2013)	2490	43.4%	7061

Manning's 2013 season leads the group only in Effective Yards, which is mostly a result of his incredible usage rate. On a per play basis, he was significantly better on 2004, as his DVOA shows.

It's easy to get caught up in the story building behind Manning's season. One of the greatest players ever, coming off a gut-punch loss in the playoffs, starts the year by torching the defending Super Bowl champions and lights the league on fire the rest of the season.

And all of this from a guy who turns 38 this offseason.

It was another great regular season from the greatest regular-season quarterback in the history of the NFL. No, it wasn't the greatest season by a quarterback ever, but it was one of the most fun to watch -- unless you're a fan of an AFC rival.

While "greatness" is a nebulous term, oft used to describe something the user struggles to define, the greatness of this storybook season will be written in the postseason. None of the quarterbacks on the above list won a Super Bowl in his record-setting seasons. In fact, only Tom Brady even made it past the divisional round of the playoffs.

But lucky for Manning, he can still go into the postseason, rewrite the narrative about his playoff failures, win it all and cement his place in history.