My point was to show that Manning has not been deprived on playing with teams with solid defenses. Has Brady played on teams with more years with decent defenses? Yes. But that doesn't mean Manning has been stuck with terrible defenses many times.
In any event, here are the post-season numbers for NE and IND/DEN defenses (looking only at post-season games):
Brady has played in 31 playoff games and the Patriots have allowed an average of 20.23 ppg in those games.
The offense gave up two points in those games, making the adjusted ppg total allowed by the defense 20.16 ppg.
Manning has played in 26 playoff games and IND/DEN allowed an average of 21.88 ppg in those games.
The offense gave up 32 points in those games, making the adjusted ppg total allowed by the defense 20.65 ppg.
Essentially, the Patriots defense allowed 0.5 points per game less than Manning's defenses have in the post season.
It may not be your intention but it really comes off as you trying to suggest that Manning and Brady have been playing with equivalent support, particularly from the defense, throughout their careers. By any measure that is just not the case and you can try to break down the data to reinforce that point any number of ways but data can also work the other way (Brady has a top 10 defense 8 out 10 times compared to Manning who has a top 10 defense 4 out of 10 times).
These are ultimately subjective arguments trying to split hairs between two of the greatest of all time. Brady has been incredible as has Manning, my subjective opinion is that Brady would not have accomplished as much had he and Manning switched places and Manning would have done at least as much as Brady. YMMV.
Again, my point is still that Manning has had opportunities to win more than he has, and people simply falling back on Brady had defenses that were leaps and bounds better doesn't pass the smell test to me.
Looking at the regular season numbers for both QB's team defenses, the Patriots defense allowed an average of 300 points per season. Filtering out the points given up by the offense, the adjusted total is 287 points. The Colts and Broncos averaged 340 points allowed per season. Filtering out the points allowed by the offense, the adjusted total is 325 points per season. That's a difference of a little more than 2.3 ppg. Manning had some poor defenses in the early going. From 2002 on, the scoring difference between Brady's teams and Manning's teams drops by a point per game to 1.3 ppg.
For much of his career, Manning played his home games indoors on turf, with no cold, wind, or snow to deal with. I don't know exactly what the difference in indoor scoring vs. outdoor scoring is, but I would guess it has to be at least 3 points per game. Apply that to the numbers I listed off, and IMO there is not a lot of statistical evidence to show that the Patriots defenses were significantly better overall than Peyton's team's defenses. I posted earlier the difference in the post season was only about a half a point a game on average in favor of the Patriots.
Were the Pats defenses better in several years? Yep. Did they rank higher more years than Manning? Yep. Did the Pats defense come up with big play in big games? Yep. Did Brady have better coaches along the way? Also yep.
But Manning also had the benefit of playing in 3 more seasons compared to Brady. And if NE invested more into their defense most years than the Colts did, Peyton's teams certainly invested more in their skill position players than NE did. Does that cancel out the gains NE had on defense? Who knows.
The whole ranking in the Top 10 in points allowed is also an arbitrary marker. This year, if NE allowed one more score they would not have ranked in the Top 10.
Bottom line, we will never know what would have happened if the two players switched teams. As I have argued for years, football is a team game, and pinning wins and losses on quarterbacks is pretty silly, as there are so many other players on a team. Sure, Brady "lost" two SBs. Yet his team held the lead after 59 minutes in both losses. But some how Brady gets the blame for losing those games when his defense gave up scores in the final minute.
So yes, Brady had more opportunities to win than Peyton has over the years, but I don't think the ledger is as lob-sided as some people make it out to be. And for the record, I have been in the camp that Manning was the better QB but that Brady has a better resume when it comes to winning titles (which is a team thing, not an individual thing).