Transplanted New Englander living in Chicago. I can tell you that the Bears indeed run hot or cold. Not only from game to game, but also from one half to the next or quarter to quarter.
They have some very impressive skill position talent on offense. I think the Patriots stand a good chance of having success against the Bears pass attack if they mix zone and man coverages, confuse Cutler, and get consistent pressure on him. The right side of the Bears offensive line is a burgeoning weak link (hello, Jordan Mills).
I would be hesitant to play strictly man against these giant receivers and tight end, as Cutler can (and has) just lob it up and let his boys go get it.
Forte is the one that the Patriots defense will have a tough task of defending, as he is the most productive combo tailback running/receiving in the league ATM.
The Bears defense has been a lot better than it was last year, especially against the run. However, their starting linebackers are not very good.
In fact, when all three starters (e.g. Lance Briggs, D.J. Williams, Shea McClellan) were out against Atlanta, and they had to start three raw players (Jonathan Bostic, Christian Jones, Kassem Green), the Bears defense was very impressive against a potent Falcons offense that usually lights opponents up at the Georgia Dome.
Trestman hinted that he may shake up the linebacking unit this week, but I doubt it. If not, then Brady, with good protection, will carve up the Bears defense in the intermediate to deep middle of the field, as the Bears linebackers and safeties are their weakest units. The Bears linebackers are simply clueless when it comes to disrupting the routes of tight ends at the LOS, as they repeatedly fail to do so game after game after game. Gronk and Wright should eat this Sunday.
The biggest problem with the Bears is coaching. They repeat the same errors almost every week, and Trestman does does not come across through both actions and words, as a leader of men. He seemingly runs a very loose ship, as yesterday's locker-room circus attests.
So overall, if the Patriots tighten up the run defense and play like they have the last three weeks, I love their chances this week at home against a talented albeit undisciplined opponent.