Over the next two weeks, we will take a position-by-position look at where the Vikings stand heading into the offseason after their 7-9 season in 2014. Today, we take a gander at the cornerbacks.

After head coach Mike Zimmer took the job in January, no position group was more scrutinized by the respected former defensive coordinator during spring workouts than the cornerbacks. Zimmer, who got his start in the NFL coaching defensive backs for the Cowboys two decades ago, was all over those guys from the start, particularly Xavier Rhodes, who was entering his second season.

The extra attention paid off, particularly for Rhodes, as improved cornerback play helped the Vikings improve from 31st in the NFL in pass defense in 2013 to seventh this past season.

Rhodes blossomed under Zimmer's tutelage and in the second half of the season was one of the league's stingiest cornerbacks. But he wasn't the only one to show improvement. Josh Robinson had some rocky moments (ahem, the first Bears game), but he bounced back from a tough 2013.

Still, despite the emergence of Rhodes, the signing of Captain Munnerlyn and the rebounding of Robinson, the Vikings have plenty of room for improvement at cornerback this offseason.

ONE REASON FOR OPTIMISM: The Vikings may have a lockdown cornerback in Rhodes. How good was he in the second half? From Week 9 on, only three players — Richard Sherman, Darrelle Revis and Chris Culliver — allowed passes to be completed less frequently than Rhodes, according to Pro Football Focus. His rapid development emboldened Zimmer to tweak his scheme so that Rhodes could match up 1-on-1 with the opponent's top wide-out. Rhodes fared well against Calvin Johnson, Mike Wallace and Alshon Jeffery down the stretch, so look for it to continue in 2015.

ONE REASON FOR CONCERN: When they Vikings signed Munnerlyn to a reasonable three-year, $15 million contract last offseason, they did so knowing the value he could potentially bring as a slot defender. They also knew that he could start in the base defense if needed. It turned out that he was indeed the best option, but he had trouble adapting to Zimmer's schemes and the result was an uneven season as a starter. Munnerlyn must play better in 2015, especially if he's still starting.

GRADES WITH A GRAIN OF SALT: Since the Vikings (understandably) won't make their player grades public, we turn to Pro Football Focus, whom some players and coaches have been critical of. For context with these grades, a grade of 0.0 is considered average. Positive grades are good. Negative grades are not. The team's top three corners all finished with positive grades. Rhodes led the group with a plus-3.3 grade (he was a plus-7.3 in pass coverage). Robinson was a plus-2.6. And Munnerlyn was slightly above average at plus-0.3. Marcus Sherels and rookie Jabari Price both received negative grades in limited snaps as reserves.

STAT THAT STANDS OUT: 18 — pass break-ups for Rhodes, which tied for fourth in the league.

POTENTIAL DEPARTURES: The Vikings have no pending free agents at the position. And while there has been a little speculation that Munnerlyn could be released, he's expected to stick around.

OFFSEASON LEVEL OF NEED: Between moderate and high. The Vikings were a top-10 pass defense with the guys they have, and while they might not desperately need another starting corner, it certainly would be a smart investment. If they can find in free agency or the draft another cornerback with some size to line up on the opposite side of the formation from Rhodes, they could keep Munnerlyn strictly on the inside as a nickel cornerback (it's worth noting that Zimmer remarked last week at the Senior Bowl "that's probably what he is") and could have Robinson on the bench in the event of an injury. So it wouldn't be surprising if the Vikings ignored greater needs and used a high pick on a corner, especially because it typically takes them a couple of years to develop.