While it's early yet, after 6 games Peyton Manning is currently on pace to have statistically perhaps his best season or second best season of his entire career.
Right now, after 6 games, he has a 67.8% completion percentage, which would be about 1% lower than his 2008 & 2009 completion percentages of 68.8%.
He has 1,808 passing yards. That puts him on pace to have 4,821 yards on the season, which would be a career best (2010 4,700).
He's thrown 14 TDs in 6 games which puts him on pace for 37 TDs, which would be second only to one of his MVP seasons when he threw 49 in 2004 (49 back in 2004 is just insane -- it's an incredible feat like Bob Beamon long jumping 29 feet 2 1/2 inches in the '68 Olympics, which is still the Olympic record to this day).
But, as incredible as 2004 was he threw for "only" 4,500 yards. He's a good bet to top that this season if he continues at his current pace.
His QB rating of 105 would be his second best season after 2004's stratospheric 121.1 QB rating.
His yards per pass of 8.0 would be 3rd in his career after 2004 (9.2) and 2005 (8.3).
He has 4 INTs after 6 games which translates to 10.6 (10 or 11) over the course of a season. Ten INTs for the season (and remember that the only pick he's thrown outside the 1st quarter of the Atlanta game was last night -- Willis's fault for not breaking off his route on a blitz pickup), would tie him for 2nd fewest in his career (9), with 2003, 2004 & 2005). Unless he has another bad game or two, he seems unlikely to have more than 10 on the season.
The one statistical area where he's having a bad year is sacks. He's been sacked 10 times, which would translate to 26 on the season, 2nd most in his career and most since 2001. That's mostly on Denver's OL and RB/TEs in pass-blocking.
The OL struggled early, giving up 8 sacks in the first 3 games, but only 2 against the Texans in the last 3 as the OL cohesion has improved as the season goes along. Manning is clearly not any easier to sack than he's ever been.
There is of course no guarantee that Manning will keep up his current pace, but in general, he's obviously improving as the season goes along. And the teams the Broncos play from now on are going to be generally easier than the murderers row of Steelers, Falcons, Texans, Patriots. They should sweep the division and Bengals and Ravens look to be the sole quality opponents left on the schedule. His numbers in short might well improve rather than decline, although they might run the ball more if they get a big lead in some games.
It seems like Manning's fanatically determined to prove himself this year. When you consider the injury plus long layoff imposed rust, plus accommodating himself to a new team his season is probably the most remarkable of his entire career -- at least so far.