As I've pointed out before, back when Manning had a better passer rating than Brady, Brady nevertheless had a higher passer rating in dome games and in games played outdoors. The only reason Manning's passer rating was higher was that everybody plays better indoors than outdoors, and Manning played far more games indoors than Brady did.
This is why the NFL needs to come up with a statistic like ops+ and era+ in baseball. That ops+ and era+ number takes into account (1) the stats, (2) the stadium factors, and (3) the era in which the guy played. In other words, Pedro Martinez' 1.74 era in 2000 is FAR more impressive than Sandy Koufax' 1.73 in 1966. Why? Because Pedro's 1.74 was done in the midst of the greatest offensive era in history, and it translated into a 291 era+. Koufax was still tremendous, but it was done in the midst of a great pitchers' era, and it translated into a 190 era+. Pedro's era was 0.01 worse than Koufax's, but it was a FAR better season given the era in which they pitched.
Comparing Brady to Manning...let's look at two years where their passer rating was similar.
Brady (2009) - 65.7%, 4398 yds, 28 td, 13 int, 96.2 rating
Manning (2007) - 65.4%, 4040 yds, 31 td, 14 int, 98.0 rating
In 2007, Manning played:
- 8 home games in a dome
- 7 road games in a warm weather site
- 1 road game in a cold weather, outdoor site (at Bal, on Dec 9)
In 2009, Brady played:
- 6 home games in a warm weather site (defined for our purposes as a Northeast site before Dec 1)
- 2 home games in a cold weather, outdoor site
- 7 road games in a warm weather or dome site
- 1 road game in a cold weather, outdoor site (at Buf, on Dec 20)
So just 1 of Peyton's 16 games was in an outdoor, cold-weather site, but 3 of Brady's were. That can have a huge impact on passing stats and passer rating. And in several years the difference was even bigger than 3 games to 1.
So an adjusted passer rating figure like ops+ or era+ would be really helpful.
