MANKATO – The Vikings reside in a division that features a trio of starting quarterbacks who combined to pass for 12,295 yards and 78 touchdowns last season. Six times the Vikings defense must face one from that group of Aaron Rodgers, Matthew Stafford and Jay Cutler.

The non-NFC North portion of their 2013 schedule also offers an eclectic mix of quarterback savvy with the likes of Ben Roethlisberger, Cam Newton, Eli Manning, Tony Romo, Robert Griffin III, Russell Wilson and Joe Flacco. And, of course, that says nothing of the laundry list of top-shelf receivers on the docket.

Conversely, the Vikings will counter with a group of cornerbacks that includes a fourth-year veteran who has amassed zero career interceptions, a rookie first-round pick and a guy who has never played the slot nickel back role but is being asked to replace Antoine Winfield.

"There are a lot of question marks," coach Leslie Frazier acknowledged.

That's putting it kindly. While Christian Ponder's development at quarterback remains an overriding narrative that ultimately will determine this season's fortunes, the state of the Vikings cornerback position might be of equal concern at present.

The team's decision to cut Winfield this offseason cost the Vikings their best cornerback and left them with more questions than answers at a position that has become immeasurably important in today's pass-happy NFL.

This passing craze has put a premium on cornerbacks and turned the nickel role into a more prominent job. Teams typically employ an extra defensive back at least half the time now, which means defenses essentially need three starting corners. The Vikings face unknowns at all three.

"People spread you out now and if you have a weakness at that position it will affect your defense," Frazier said.

In Winfield's absence, the leader of that position becomes former second-round pick Chris Cook, who has missed more games than he's played (22) in his first three seasons and still has not recorded an interception.

"This is basically a put up or shut up year," Cook said. "I'm ready to do it."

For the Vikings' sake, Cook needs to do enough to finally justify his status as a high draft pick. Cook remains a physical corner who has shown flashes, but injuries and legal issues have prevented him from playing long enough to determine his true value as a player.

A pair of knee injuries limited him to six games as a rookie. Legal problems stemming from a domestic assault arrest (he was later acquitted at trial) cost him most of the 2011 season. He played in 10 games last season, missing six because of a broken arm.

If Cook can't stay on the field this season, an already thin position will be put in a precarious and unforgiving predicament.

"It's a big year for him," Frazier said. "It's a contract year for him so he has a lot going on. He's been a very good player for us when he's stayed healthy. We're counting on him in a big way."

That's because Cook is the surest thing in that position group. First-round pick Xavier Rhodes has ideal size (6-1, 210 pounds) and has displayed in camp a willingness to play physical at the line, but every rookie faces a learning curve. And Josh Robinson is making the switch to the nickel role that Winfield manned so superbly.

The team's unwillingness to pay Winfield's $7.25 million salary might have been sound business, but his departure leaves a hole in the defense that won't be easy to plug. Frazier admitted that coaches are still trying to determine Robinson's instincts in that role and his acumen as a tackler, which is something Winfield does better than any corner in the league.

"There's a hole there that we have to fill," Frazier said. "We think we have the players on the roster to get that done, but now we have to go out on the field and actually do it."

Given the quarterbacks on their schedule, that shouldn't take long to find out.

Chip Scoggins • ascoggins@startribune.com