Vikings defensive coordinator Leslie Frazier believes the NFL has become much more of a passing league than a running league.
"You don't see a lot of people sticking to the run, like they used to, but it has definitely become a passing league without question," Frazier said. "When you play against some good quarterbacks and the good receivers that we have, it is a challenge, there is no question about it. I think the numbers are up across the league as far as yards by quarterbacks and [completion] percentages, but that is the way the league has gone. You have to work hard to defend the pass in the National Football League."
Frazier said teams also have found ways to keeping the Vikings' two best pass rushers -- end Jared Allen and tackle Kevin Williams -- from getting to passers such as Bears quarterback Jay Cutler, who passed for 273 yards and four touchdowns against the Vikings on Monday.
"[Allen] is getting a lot more double-teams, [with teams] keeping the back in, keeping the tight end in," Frazier said. "They are doing a lot of things to keep him away from the quarterback, and we have to find a way to get him free.
"They are keeping that tight end to block Allen and they will slide the center and the guard sometimes to Kevin [Williams], and then there are some times Kevin will get a one-on-one. He will have to win in those situations, but most of the time it is a double-team on Jared."
Frazier said there is no question cornerback Antoine Winfield is struggling because of the foot injury that caused him to miss six games earlier this season.
"Right now he is struggling a little bit with that injury, and we have to do some things to help him," Frazier said, "but the [Bears' winning touchdown reception in overtime] is an easy play for him. He is a All-Pro corner when he is healthy."
Then, of course, the Vikings miss E.J. Henderson, the best middle linebacker in the league, who broke his leg Dec. 6 against Arizona.