New England quarterback Tom Brady has struggled throwing the ball deep this year. Will he find his form against Buffalo on Sunday? (US Presswire)

Patriots at Bills -- Week 4

Where: Ralph Wilson Stadium, Buffalo, N.Y. (turf, outdoors)

When: Sunday, 1 p.m. ET (CBS)

Spread: Patriots by 4

Forecast: Rain likely; projected kickoff temperature expected to be in the upper 50s

Records: Patriots (Overall: 1-2, AFC East 0-0); Bills (Overall 2-1; AFC East 0-1)

Past results: Two most recent meetings -- Jan. 1, 2012: Patriots 49, Bills 21; Sept. 25, 2011: Bills 34, Patriots 31. Series record: Patriots hold a 62-41-1 lead. 

What matters: A lot has changed since these teams last saw each other -- and maybe not in the way New England hoped. The Patriots' revamped defense went through a harsh regression last week by giving up more than 500 yards and recording just one hit on Baltimore's Joe Flacco in the team's first true test of the season. The addition of WR Brandon Lloyd and emergence of RB Stevan Ridley was supposed to make a strong offense unstoppable, but a new emphasis on passing outside the numbers and running the ball between them has only created confusion for Wes Welker and Rob Gronkowski, last year's top targets. It's too soon to box a team into a must-win situation, but the Patriots need to find their identity this week against Buffalo if they want to avoid a do-or-die game in the near future.

Who matters: People in the New England region have seen more of Gronkowski during commercial breaks in Dunkin' Donuts ads than during games. While some have been quick to say his slow is due to him taking on a larger role as a blocker, it simply isn't true. The tight end ran more than 30 routes last week against the Ravens and finished with two receptions for 21 yards on three targets. The Patriots need him to re-emerge as a focal point.

Key matchups: Cornerback Devin McCourty, who quietly had a good game last week before a costly pass interference penalty in the waning moments, will need to put together a strong performance against Buffalo's Stevie Johnson if New England is to avoid a third consecutive loss. Johnson got the best of McCourty by catching all four passes thrown to him for 38 yards when the two were lined up against one another during a Week 3 game last year. McCourty played safety in the second meeting. ... How the Patriots offensive line performs against Buffalo's improved pass rush, which has recorded nine sacks -- the three other AFC East teams have 10 combined -- will also be a key area to monitor.

Injuries of note: TE Aaron Hernandez will not play due to an ankle sprain. OL Logan Mankins has shown up on the injury report throughout the week with a hip injury and could be in jeopardy of missing Sunday's game.

Inside stuff: P Zoltan Mesko is averaging a league-worst 38.3 yards per punt, but is third with seven kicks inside the 20-yard line. The Patriots need to remain efficient in this area against Buffalo's Leodis McKelvin, who averages 29.7 yards per punt return.

Connections: Bills DE Mark Anderson played for the Patriots last season and tied for the team lead with 10 sacks. ... Bills TE Lee Smith was fifth-round pick of the Patriots in 2010. He was released after his first training camp. ... Gronkowski grew up in the Buffalo area. ... New England DE Trevor Scott played football at the University at Buffalo.

Stat you should know: If the addition of Lloyd was supposed to help Brady's deep game, it's yet to show on the field. Brady is 5 for 13 for 170 yards on balls thrown at least 20 yards, placing him 15th in the league in terms of completion percentage (38.4 percent). Carolina's Cam Newton's 56.2 percent (9 for 16) ranks first.

Looking ahead: Denver at home, Seattle on the road, the Jets at home -- things could quickly spiral out of control the next three weeks if the Patriots don't shake out of this early lull. They simply can't afford to lose this week.

Prediction: Patriots 34, Bills 24

Nick Underhill covers the Patriots for MassLive.com. Follow him on Twitter @CBSPats or @nick_underhill.