Notwithstanding last week's demolition of the Eagles in open-air Philadelphia, or multiple years playing outdoor pro football at a high level in San Diego, speculation runs that Brees is a better indoors quarterback than outdoors quarterback.
Some statistics that we have compiled on Brees as a quarterback indoors v outside through his 52 games as the Saints' quarterback are below. We counted both Dallas and Houston away games as indoors.
Average completion percentage Indoors: 67.97%, outside: 63.88%
Average passing yardage Indoors: 294.27 yards, outside: 287.63 yards
Average passing touchdowns Indoors: 2.00, outside: 1.79
Average interceptions Indoors: 0.97, outside: .89
Average QB Rating Indoors: 100.04, outside: 91.07
Win/Loss Record Indoors: 19-14, outside: 9-10 (Superdome: 15-11)
There you have it. Speculation that Brees is better indoors than outside is justifiable to this extent: he throws slightly fewer interceptions outside, and is marginally better in all other passing stats while indoors.
Take what you will from those statistics. He's still a damn good quarterback regardless of the turf or the sky.
And while his three statistically worst career games all came outside (at Cleveland and at Chicago in 2003, at Washington in 2005), his worst career game as a Saint was on that fateful Monday Night matchup in the Superdome. An high Brees pass to Deuce McAllister tore the runningback's ACL, and four Brees interceptions that night sent the team into their early bye week at 0-3.