The big story heading into this weekend's highly-anticipated game between the 7-1 Vikings and the 6-2 Bills is the status of Buffalo quarterback Josh Allen, who may or may not be able to play through an elbow injury. If Allen can't play and that's starting to seem more and more likely Case Keenum would step in at QB against his former team, and the Bills' offense would become notably le s dangerous.That's an unknown situation, though Vikings head coach Kevin O'Connell said they have to prepare as if Allen will play. One thing is certain: no matter who ends up throwing pa ses for the Bills, their elite defense even with injury concerns of its own will pose a major challenge for O'Connell, Kirk Cousins, and the Vikings' offense on Sunday.Nine weeks into the season, the Bills lead the NFL in scoring defense, allowing 14.8 points per game. They've Billy Turner Jersey held three opponents to 10 points or fewer and haven't allowed more than 20, despite facing each of the league's top three teams in offensive DVOA (the Chiefs, Dolphins, and Ravens). Buffalo also ranks fourth in total defense, allowing 299.6 yards per game. The advanced metrics are just as impre sive: the Bills rank fourth in defensive DVOA they're the only team in the top six against the run and the pa s and fifth in defensive EPA per play.This Bills' defense, led by head coach Sean McDermott and defensive coordinator Leslie Frazier, is an elite unit with playmakers at all three levels."Every piece that you could make mention of Jermichael Finley Jersey , theyre doing well," Cousins said. "I think it starts with a great scheme. They play very fast, they play hard. I think they play well as a unit. They have the players on all three levels of defense. They cover well, they tackle well, they create turnovers well. You can go down the line of attributes you want in a defense, and theyre checking those boxes."The Bills have 15 takeaways this season, which is tied for fourth-most in the league and one ahead of the Vikings' defense. 11 of those have come on interceptions; only the Eagles, who picked off Cousins three times in Week 2, have more. Safety Jordan Poyer, a first-team All-Pro last season, leads the way with four INTs.Buffalo's defense doesn't utilize a super complex scheme or a wide range of looks. It's actually a fairly straightforward defense from a schematic standpoint; the Bills are similar to the Vikings in that they use a lot of two-deep safety looks and don't blitz much, trusting their front to generate pre sure while rushing four or five. Their defense is great because it's coached well and they have talented players who execute their responsibilities at a very high level."First and foremost, I think they don't try to reinvent the wheel defensively, and thats the challenge," O'Connell said. "A lot of times, you can know where they are and what theyre doing, but they play really hard and theyre really good players. They have great technique, fundamentals. Any ball that gets tipped, seems like it ends up in their hands. Any time youre not extremely dialed into the protection responsibilities, anyone on their front can beat you at any time, so its going to be a challenge to throw it, and when you try to run it, theyve got defensive Darnell Savage Jr. Jersey backs that fit the run as well as any team in this league."It starts up front for the Bills. Even at 33 years old, Von Miller is still one of the best pa s rushers in the league. He leads the team with seven sacks and 29 pre sures. 2021 first-round pick Greg Rou seau is having a Isaiah McDuffie Jersey strong season(5 sacks, 23 pre sures)opposite Miller, and there's depth at defensive end with veteran Shaq Lawson and recent second-rounders A.J. Epenesa and Boogie Basham. They go four deep on the interior with DaQuan Jones, Jordan Phillips, Ed Oliver, and Tim Settle.Scroll to ContinueThe Bills also utilize plenty of stunts and games with their front, which is something the Vikings' interior offensive line has struggled with at times this season, including last week in Washington."You hear a lot about, on offense, things that look the same that are different they can play their coverage schemes from very similar looks," Vikings offensive coordinator Wes Phillips said. "Theyre not a huge pre sure team, theyre fundamentally sound, they move the front a lot which is sometimes harder than pre sures, picking up the stunts, those types of things. Theyre really just between coach McDermott, coach Frazier got a lot of respect for those guys. Wherever theyve been, its always been a challenge playing against their defense."On the second level, the Bills have two excellent linebackers in Matt Milano and Tremaine Edmunds. Poyer leads the way on the back end, and it's po sible two-time All-Pro cornerback Tre'Davious White will make his season debut this weekend. Dane Jackson, Christian Benford, rookie first-rounder Kaiir Elam, and nickel Taron Johnson round out the cornerback group. Two-time All-Pro safety Micah Hyde is out for the year, but 2021 sixth-round pick Damar Hamlin has filled in nicely.Basically, there's talent all over the place. Draft pedigree isn't everything Poyer, Hyde, and Milano are former late-round picks but this defense boasts a whopping six former first-rounders in Elam, Rou seau, Oliver, Edmunds, White, and Lawson. The Bills' front office has invested a ton of draft capital into the defense and it has paid off. It's a dominant unit that complements Buffalo's similarly-elite offense, which is why this team is among the favorites to win the Super Bowl.The Bills' run defense has been good for most of the season, but it slipped in recent weeks. They gave up 174 rushing yards in a surprising lo s to the Jets last week and allowed the Packers to run for 208 yards the Aaron Rodgers Jersey week prior.That suggests the Vikings might be able to get Dalvin Cook going in this game. However,before their Week 7 bye, the Bills had allowed over 100 rushing yards just once, against Lamar Jackson and the Ravens.The primary concern with the Bills, on both sides of the ball, is health. Offensively, they need Allen to get healthy. Defensively, they have a ton of players who are banged up right now. Poyer and Milano mi sed the Jets game and Rou seau injured his ankle during the game. White still hasn't played all year while recovering from an ACL injury. Milano should return against the Vikings, but Poyer, Rou seau, Edmunds, and Elam all mi sed Thursday's practice, putting their availability for Sunday into question.Still, even if the Bills are mi sing a few pieces, their defense is going to be tough to play against. They have star power, they have depth, and they have great coaching. It's going to be an awfully big JJ Molson Jersey challenge for the Vikings' offense, and we should learn a lot from this specific matchup when the Vikings have the ball."You really have to have a tight plan, a tight scheme (offensively)," O'Connell said. "And then you throw in the noise and the challenge of that environ