Anybody that thinks the Pats window is closing or if Tom Brady is on the decline is absolutely insane. Let's look more closely as to why the Patriots haven't done as good the past 3 years.
Defense. That is what wins you championships (special teams included). The 2001 was a stat anomaly to say the least. However, if you look at the Post season stats for the 2001 year, you'd see they were 2nd in points allowed for defense during that post season. It was a team that started clicking at the right time. The main staple of the BB teams has been it's relentless defense, with Tom Brady being the clutch guy that drove them down in the last minute to win the game or put them in a position to win. (ie..Field Goal)
To be quite honest, the 2005 and 2001 years they were fortunate to have been playing in a very craptastic division. Up until 3 years ago, the AFC East was a laughing stock, like our NFC West currently is.
Say what you want, but most of us Redskins fans would give our left nut to have records like they have over the past decade. (3 Super Bowls) Bad news is, they are going to get better. With 2 picks in each of the first three rounds in this years draft, the rich keep on getting richer.