For me it's the Miami game.
The Jet's game was on the road, against a division rival. A rival who knows you inside and out. A rival with a pretty good team with an above average defense. A rival that still had something to play for. And I believe that the Pats went into that game with one goal and that was to win it. They fought tooth and nail to win that game. It just didn't happen.
There was no shame in losing that game.
But Miami, sure they are a rival, but they were in disarray, with nothing to play for, with U-Haul's warming up in the parking lot. And the Patriots didn't even try to win that game, well, maybe a little bit in the second half. What did they open with.... tons of running plays and then opened up the offense a little bit in the third quarter? They should have come out and tried to break Miami's spirit from the opening kickoff. They didn't. They let Miami hang around and shorten the game to the point that the Dolphins said... what the heck, let's try and win one. And they did.
This is the game that will haunt me as we move on from 2015. Home field is everything in the playoffs and we let it slip through our fingers and into the hands of a team we historically have crap-ass success against in the playoffs.
It was ours for the taking and we decided not to take it.