It's just a good example of the FACT that in the NFL the talent gap between the best teams and the worst is minimal. Every guy on the field is a GREAT football player. So we shouldn't be surprised when a so called "bad" team beats a good one.
This game was lost because of all the usual reasons. A fumble gives them the ball deep in our own territory. Another fumble takes a sure 7 off the board. We failed to control the run game. A bunch of drops IIRC. Cleveland played very well. THEY made all the key plays, and the Pats played like sh!t. They have one or two of these types of games every year. BB loves them to the extent that they are such great teaching tools.
Also remember that 2010 was supposed to be a down year as the Pats were in the middle of a significant roster rebuild after that very disappointing 2009 season. But that 2010 draft was special and the "rebuild" was short lived. They had a decent 2010 season and made the superbowl the next year with one of the worst defenses in the history of the league.