That's a pretty thin margin for error. Fail to win the turnover battle, or Brady has a slightly off day, or some key drops, and the balance can tip pretty easily. In the playoffs, with better defenses putting more pressure on Brady and teams executing better overall, it's easier for one or more of those 3 things to happen.
And, as we've seen, when the Patriots have lost in the playoffs recently, some combination of these things always seem to happen.
2007 loss to NYG - 22 first downs, 274 total yards. Brady: 29-48 (60.4%), 266 yds, 1 td, 0 int, offense scores just 14 points. Turnovers: NYG 1, NE 1
2009 loss to Bal - 15 first downs, 196 total yards. Brady: 23-42 (54.8%), 154 yds, 2 td, 3 int, offense scores just 14 points. Turnovers: Bal 2, NE 4
2010 loss to NYJ - 26 first downs, 372 total yards. Brady: 29-45 (64.4%), 299 yds, 2 td, 1 int, offense scores just 21 points. Turnovers: NYJ 0, NE 1
2011 loss to NYG - 21 first downs, 349 total yards. Brady: 27-41 (65.9%), 276 yds, 2 td, 1 int, offense scores just 17 points. Turnovers: NYG 0, NE 1
2012 loss to Bal - 28 first downs, 428 total yards. Brady: 29-54 (53.7%), 320 yds, 1 td, 2 int, offense scores just 13 points. Turnovers: Bal 0, NE 3
Common themes:
(1) Subpar performance by Brady. None of these performances would we give Brady an "A". Most not even a "B". His cumulative stat line in these five losses is: 137-230 (59.6%), 1315 yds, 8 td, 7 int, 74.5 rating. This is *not* what we expect from our HOF quarterback.
(2) Losing the turnover battle. The Patriots, over the past handful of years, have been among the best teams in the history of the NFL at taking care of the football. And they've also been one of the best in the league at creating turnovers. And yet in these five games they are -7 in the turnover battle, and not one time out of these five did they win the turnover battle. They have had playoff games where they've lost the turnover battle and still won the game, but in all five of their recent playoff losses, they've never been on the plus side in turnover margin.
(3) Inefficient offense. Whether it's bad penalties (Brady's intentional grounding last year), dropped passes, missed receivers, inability to execute in the red zone, whatever. Suddenly the machine that is the Patriots' offense has ground to a halt in these games.
Here are their regular season game averages vs. their stats in these five games:
First Downs
Year - Reg. Season Avg - Playoff Loss
2007 - 24.6 - 22 (-2.6)
2009 - 23.3 - 15 (-8.3)
2010 - 20.9 - 26 (+5.1)
2011 - 24.9 - 21 (-3.9)
2012 - 27.8 - 28 (+0.2)
AVG - 24.3 - 22.4 (-1.9)
Yards Gained
Year - Reg. Season Avg - Playoff Loss
2007 - 411.3 - 274 (-137.3)
2009 - 397.3 - 196 (-201.3)
2010 - 363.8 - 372 (+8.2)
2011 - 428.0 - 349 (-79.0)
2012 - 427.9 - 428 (+0.1)
AVG - 405.7 - 323.8 (-81.9)
Points Scored
Year - Reg. Season Avg - Playoff Loss
2007 - 36.8 - 14 (-22.8)
2009 - 26.7 - 14 (-12.7)
2010 - 32.4 - 21 (-11.4)
2011 - 32.1 - 17 (-15.1)
2012 - 34.8 - 13 (-21.8)
AVG - 32.6 - 15.8 (-16.8)
I mean, look at that last list for a minute. That's a serious indictment of the offense. Could it just be the matchups? I mean, the Giants and Ravens - who have combined to beat the Patriots in 4 of these 5 games - typically give NE a difficult time. So that's a possibility. But wow, the Ferrari that is the Pats' offense has become a VW Beetle in these playoff losses.
EDIT: And of those 5 playoff losses, 3 were at home, and 2 were on neutral fields. Not a single one of them was on the road, where you would naturally expect a dropoff.