Captain Munnerlyn's eyebrows rose when a TV reporter stuck a probing microphone in his face and asked how much pride he took in the Vikings being ranked fourth in the NFL in pass defense.

"Oh, we're No. 4? Wow," the cornerback said Tuesday. "I didn't know that one."

Yes, it's true. These Vikings — not to be confused with those Vikings, the ones who finished next to last in pass defense a season ago — have quietly climbed into the top five through the first eight games of new coach Mike Zimmer's tenure. So quietly, it seems, that some Vikings defenders weren't even aware of just how well they have defended the pass of late.

But after holding two of their past three opponents to fewer than 200 yards passing, the Vikings find themselves looking down at traditionally stingy units such as the San Francisco 49ers and Baltimore Ravens, the focused Detroit Lions defense that everyone is raving about, and even the Seattle Seahawks' brash and boisterous Legion of Boom.

"I like the way they've played the last three weeks," Zimmer said when asked about the ranking. "Again, talk to me at the end of the season and I'll tell you what I think. There's a long way to go."

That No. 4 ranking might be a little misleading (they are 12th in yards allowed per pass attempt, a more telling stat). And their recent fourth-quarter failures are certainly concerning (two blown leads the past two weeks). But there is no denying the Vikings are vastly improved from a season ago when it comes to disrupting quarterbacks and slowing down their receivers, which are musts in today's NFL.

Second-year Vikings cornerback Xavier Rhodes tackled Buccaneers wide receiver Mike Evans during the second half of Sunday’s game in Tampa, Fla. The Vikings gave up only 38 passing yards to Tampa Bay through three quarters.

"Everybody is doing their jobs," cornerback Josh Robinson said. "The guys up front are hitting home. The rush and coverage are working together. So things are going much better."

Last season, the pass defense was the leakiest in team history, and that's saying something, because the Vikings have had some less-than-stellar seasons in recent years. They allowed 287.2 passing yards per game, and the 37 touchdowns they allowed through the air was one of the highest totals in league history and the most a Vikings defense had ever surrendered.

The Vikings replaced Leslie Frazier with Zimmer, who had coordinated a Cincinnati Bengals defense that ranked in the top 10 against the pass in four of his final five seasons there.

And once Zimmer was on board, the Vikings focused on overhauling his personnel, starting with the defensive front. They re-signed defensive end Everson Griffen and added defensive tackles Linval Joseph and Tom Johnson. They used their top draft pick on linebacker Anthony Barr, who was just named the NFL's best defender for Week 8.

With seven new starters on defense, Zimmer replaced Frazier's Cover-2 defense with a more aggressive scheme that relies more on man-coverage concepts in the secondary, though Zimmer mixes in zone with his blitzes, too. And in October, the Vikings defense finally started to jell.

"Everybody came in and worked their tails off in the offseason and everybody bought into Coach Zim's scheme and got on the same page," Munnerlyn said. "I wasn't here last year. I don't know the style of defense they ran or anything like that. I just know all the guys bought in this year. They wanted to be better than they were last year."

This year's unit wasn't exactly smothering during an early-season stretch against quarterbacks such as Tom Brady, Drew Brees, Matt Ryan and Aaron Rodgers. And the raw numbers are surely aided by the fact that Brady and Rodgers used their multimillion-dollar arms to hand the ball off because the Vikings couldn't stop the run.

But the Vikings defense has picked it up over the past three weeks. The Vikings slowed down the Calvin Johnson-less Lions. They picked off Buffalo Bills quarterback Kyle Orton four times. Then they limited the Tampa Bay Buccaneers to just 38 passing yards through three quarters. Their passing yards allowed per game has plummeted to 212.1.

The defensive backs are growing comfortable with what Zimmer is asking them to do, and the pass rush has made life easier, too, as they often look back and see a pile of purple on the quarterback. With 14 sacks the past three weeks, the Vikings now rank second with 25.

"It's definitely a good feeling," Munnerlyn said. "Those guys have been covering up for us, and we're trying to cover up for them."

The Vikings know, though, that there still is plenty to improve upon over the season's second half, which probably explains why Munnerlyn was surprised to learn that the team's pass defense ranks that high.

"It's a long season," Munnerlyn said. "To be ranked fourth right now halfway through is pretty good. But hey, we've got to keep it up. Because we know in eight games you can go from [No.] 4 to 32 easy."