Boss' big catch was a pretty clean and well executed skinny post. I assume you're talking about Tyree's catch, which I think is just more luck than anything. Speaking directly to your point, Tyree was going up to catch that ball with Rodney Harrison, and I don't think a case can be made that Harrison didn't make a play on the ball because he's not a 'tested' defensive player.
I guess your general point is that the Pats were hurt by a certain complacency that developed over the course of winning 18 straight games, many of them by wide margins. I don't think I buy that, especially considering they had to win close games in the AFC Divisional Round and Conference Championship (with, as I already mentioned, the latter being won by the defense). I'm not sure we can pinpoint an overall reason why they lost that game, and I tend to think the Giants just played a slightly better game that day, and got a few key breaks.
But I understand what you're saying, we just see this thing a bit differently.