The Dallas Cowboys defense performed well above expectations last season - or at least during the early portion of last season - despite expectations very much to the contrary.

Whether the Boys' "the whole is greater than the sum of the parts" defense can do it again next year is entirely debatable, thanks to some key losses and trouble spots that don't seem to have ready answers.

One such area of concern is cornerback, where Brandon Carr, Orlando Scandrick and the disappointing Morris Claiborne seem the only locks for the roster at the moment - they comprise the nucleus of a group that managed just four interceptions all year and just one interception over the final seven games of the 2014 season.

Additions will be made during the 2015 NFL Draft; it seems now only a matter of when.

"The #Cowboys had 6 CBs among their 30 national visits, including Marcus Peters. So there's probably a decent chance they go that way at 27," tweeted Charean Williams of the Fort Worth Star-Telegram.

While the running back position has seemed for some time the likeliest spot to see the attention of GM Jerry Jones in the first-round thanks to DeMarco Murray's defection some, including Williams and Gil Brandt of NFL.com, believe it's actually the defense and, perhaps more specifically, cornerback, which requires an injection of talent.

"But while many have Dallas penciled in to take Murray's replacement with the 27th overall pick, I actually think the Cowboys would be best served by focusing on defense in the first round," writes Brandt. "Because while Dallas wasn't as bad defensively as people feared it would be in 2014, it wasn't great, and a number of defenders, including linebacker Bruce Carter, joined Murray in heading out the door this offseason. The Cowboys should look for a corner or a pass rusher and wait until a later round to land a running back, someone like Tevin Coleman in the second round or Duke Johnson in the third."

The return to health of Sean Lee, the continued development of Anthony Hitchens and another year in the middle for Rolando McClain should all aid the center of the Dallas defense, but it's the perimeters that seem a now-major concern.

Among the cornerback prospects the Cowboys have reportedly visited with, worked out or brought to town thus far are Peters, Tray Walker of Texas Southern, Ronald Darby and P.J. Williams of Florida State and Kevin Johnson of Wake Forest.

The consistent theme for most of these players seems to be length and physicality.

Peters is a top-10 talent who has plummeted on many draft boards thanks to personality and character concerns - concerns which got him kicked off the Washington team. Williams is suffering a similar fate thanks to a pair of DUI arrests.

Their elite skills will get them drafted and, luckily for a team like the Cowboys, they could now be had at No. 27 - Williams may actually fall much farther, but big cover corners, even one's with serious off-the-field concerns, are coveted in today's pass-happy NFL.

Johnson seems the highest-rated guy at this point and one who could potentially step in for the Cowboys and start from Day One and would, at the very least, be able to contribute on special teams.

"Johnson is a three-year starting cornerback who showed great improvement in man coverage from 2013 to 2014," writes Lance Zierlein of NFL.com. "While he lacks desired weight at the position, his cover skills, athleticism and competitiveness give him a shot to come in and start right away. Johnson can play gunner on special teams."

In the end, both the running back position and cornerback are likely to see serious attention from Jones and the Cowboys in the 2015 NFL Draft, it simply remains to be seen which players fall and how the board breaks to determine which spot is attended to first.