Keep an eye on how David Harris plays when the Pats are in the red zone. His coverage of their tight ends will be the difference between touchdowns and field goals.
If Eric Smith and Sione Pouha have big games in the ways I described, then New England's trips inside the 20-yard line will be few and far between. But realistically, I'd bet the Patriots have multiple such possessions.
Quarterback Tom Brady has two large targets in Rob Gronkowski and Aaron Hernandez. They have combined for 11 touchdown receptions so far this season.
Harris won't be able to do much if Brady makes perfect throws to them.
Ideally, though, he should be able to stay in front and jump at least one predictable route for a pass deflection or interception.