The question remains Could Brady maximize that talent in the way that Manning has?
Could he win a Super Bowl with that Indy sieve of a defense?
Maybe. 1) Brady's ball control passing game may be just what the Colts need. Despite having the league's second leading rusher, the Colts have the 23rd best time of possession in the league. Their time of possession in their three losses? 24:54, 25:26, and 22:27. They've been slinging the ball for years - Manning's personal stats look great, but his style wins games, not championships.
2) Let's assume Manning's just a better passer, and that Brady wouldn't get as much out of that team. (Before we do, let me say that Brady's accuracy on the deep ball is underrated. Manning's certainly seems better, but the fact that Manning's receivers are open more often and the fact he has the threat of the play action pass gives him a little more leeway, too. Let me also reiterate that Brady's gotten more from less in bad conditions, while Manning's gotten more from more in a dome - so the assumption that Manning is just a "better passer" is not a gimme).
Now how much does Brady's cool-under-fire outweight Manning's cool-except-in-the-playoffs? Would he have been able to put up a total of one TD in his first three playoff games with Harrison and Edge at their peak? Brady did more with less offensive talent around him, including a game in a blinding snowstorm.
Would he have been completely shut out against the Jets the year before if he had a healthy Harrison, Wayne, Clark, Edge and Pollard? Brady's never been shut out in the playoffs, so it's hard to say.
Would Brady have thrown 4 picks in the last AFC Championship game? People have manhandled the Patriots' smurf receivers for years (I'm sure they always backed off exactly five yards from the line of scrimmage though).
Would Brady have won two Superbowls with the Colts? It's hard to say. But you'll have a hard time arguing that he'd have done any worse. What do Manning's stats get you? Would you or anyone take the "consecutive number of 25 TD seasons" record and the TD record over one, let alone two, Superbowls?
3) You've argued that Brady's success is all Belichick and the defense. So far I've focused on Manning's unquestionably awful personal performance in the playoffs. Let's look at team performances. Through the same point in their careers, Manning was 0-2 in the playoffs with 0 passing TDs, while Brady was 6-0 in the playoffs with two Superbowl MVPs.
Also, remember that Belichick's record in Cleveland was average at best, and that he was 5-13 in games without Brady, including an 0-2 start the year that Brady took over. Belichick and the defense weren't winning games without Brady.
So did Belichick make Brady? Or did Brady make Belichick?
4) Let's assume you disagree with all of those arguments, and think that Manning's able to do everything Brady can do and more. In that case, let's also look at their salaries. Now you're comparing Manning with Brady and the defensive players you could get if you didn't have so much money tied up in Manning. When talking about who you'd rather start a team aroud, this becomes an important question - the Pats have been able to build a Superbowl winning team around Brady. The Colts haven't been able to do the same around Manning.
Now you could argue that the Patriots' front office is better, and maybe it is. But remember that Polian was one of the most highly regarded GMs in the league. And Dungy was a defensive guru, able to find hidden gems for his defense. Until they got to the Colts. Now, they're throwing money at offense because Manning hasn't been able to develop the Pathons and Ismails of the world into a good enough WR2 to put them over the top, which means there's no salary cap left over for defense.
So if you're building a team around Manning, and you want these gaudy numbers, you have to be willing to spend A LOT on offense. Can a team in today's NFL build a winning team around Peyton Manning? We haven't seen it yet. But a team in today's NFL can build a potential dynasty around Tom Brady.