EAGAN, Minn. — Ever since Vikings Head Coach Mike Zimmer arrived in Minnesota, his defense has been known to frustrate opponents with his patented Double-A gap blitz.

Zimmer has the pieces to execute the scheme to near perfection. Linebackers Eric Kendricks and Anthony Barr crowd the line of scrimmage on each side of the opposing center, while safety Harrison Smith and a nickel cornerback each lurk on the edge of the defense.

Each player could blitz and each could drop into coverage, which usually leads to mass confusion for an opposing quarterback and his offensive line.

Yet as the Vikings put together another strong campaign on defense, Zimmer said Monday that his squad hasn't tried to get after quarterbacks out of the Double-A package nine games into the 2018 season.

"Quite honestly, I don't think we've run any Double-A blitzes this year," Zimmer said. "Because everybody is practicing them, so we do something else."

Zimmer is in his 40th season as a football coach, 25 of which have been spent in the National Football League.

Yet the 62-year-old hinted Monday that he has had to adapt more this season as teams around the NFL — ever a copycat league — have taken Zimmer's successes and implemented them to their own defensive schemes.

"They've been stealing our blitzes for a long time. They've been stealing our coverages now," Zimmer said. "I'm not saying it's all. It's similar … it may not be all the same. I told somebody the other day, there's probably 10 or 12 teams that are running, really, what our base coverage was all the time now.

"It's like the old thing, everybody copies if you've been good. So, then you've got to change up and do other things. So far, we've been doing that, and hopefully we can go back to doing some of the things we were doing before when they started adjusting to what we're doing," Zimmer added. "The whole game is about adjustments. We made a lot of them during the course of the ball game [Sunday]. Sometimes adjustments are moving the line to a different spot or it could be changing up what coverage you're playing because of the routes they're running throughout the course of the game. It's a lot of different things, but the entire time is adjusting."

Zimmer pointed at the past five games — four of which have been Minnesota wins — as evidence that the Vikings have quietly been changing their defensive scheme on the fly.

Minnesota gave up an average of 27.5 points and 381.5 yards per game in the first month of the season.

Since then, the Vikings have **20 sacks and 10 takeaways in five games**, holding opponents to just 18.4 points per game and 274.8 yards per game.

"We've had to change up a lot. For the last five weeks, probably, we've played pretty good defense," Zimmer said. "We were getting a lot of scheme things. Because we're good at what we did, people are copying it. There's a lot of teams now that are playing a style of defense similar to us.

"Now, all these offenses are attacking these defenses pretty much the same way. So, we've had to adjust and change coverages and what we've done in the red zone … [ Rams running back Todd] Gurley beat us on the one route in the red zone, which was a scheme thing, basically," Zimmer added. "So, we've had to change up a lot of things that we've done. Luckily, our players have been able to execute it. Part of it is having enough confidence to call some of these things and still be good against the run."

Zimmer said he's noticed teams have slowly taken his Double-A scheme in recent years, but added the pilferage of his defensive calls isn't anything new.

Zimmer pointed to his time in Dallas when he coached the defensive backs and the Cowboys had Hall of Fame cornerback Deion Sanders from 1995-1998.

"It always starts out slow. When I was in Dallas, we had Deion Sanders," Zimmer said. "I didn't want him playing a certain style of defense, so we were trying to allow him to be man-to-man and so what we had to do was to figure out a way where he could still be man-to-man, but we could still get extra guys and play man within the zone combinations.

"Well, we were pretty good at it, and then next thing I know, I see Philadelphia playing it. They're in our division and watch us all the time, so they're playing it," Zimmer added. "Next time you see Buffalo … you just see a gradual thing. I've had many coaches say they watch our blitz tape every week to see what we're doing. That's kind of how it starts and then they try and copy it."

The Vikings defense currently ranks sixth in yards allowed per game (322.2) and is 14th in points allowed per game (22.7).

But there is still plenty of work left to do, as Minnesota sits at 5-3-1 heading into its bye week. The Vikings have seven games remaining [three at home and four on the road], with four games against division opponents.

There may be even more changes to come, as Zimmer said there is a weekly evaluation on what he thinks will and won't work against an opposing offense that upcoming weekend.

Zimmer noted that earlier in the season the Vikings were getting burned by the screen game. But against Detroit, the Vikings snuffed out two similar plays that went for a total of minus-4 yards.

"We are self-scouting us a little bit. Like I said, some of the areas that we haven't been as good in, every Monday we come in, we start on the other team … and then we'll sit down and look at plays that hurt us," Zimmer said. "We'll go back through the season and look at plays that hurt us and kind of see if there's a pattern going on.

"We're kind of constantly doing that," Zimmer added. "Same thing offensively, so we can figure out what we have to change or adjust the coverage or make different calls or game-plan things so we don't get hurt."