Vikings position preview: Defensive backs

MANKATO, Minn. -- Before the Minnesota Vikings convene for their first practice of training camp on Friday, we'll break down the final position group in our series. Here is a look at the Vikings' defensive backs.

Returning players: Xavier Rhodes, Josh Robinson, Marcus Sherels, Shaun Prater, Robert Steeples, Harrison Smith, Jamarca Sanford, Andrew Sendejo, Mistral Raymond, Robert Blanton, Brandan Bishop

Gone from last season: Chris Cook, A.J. Jefferson, coach Joe Woods

New this season: Captain Munnerlyn (free agent from Carolina), Derek Cox (free agent from San Diego), Kurt Coleman (free agent from Philadelphia) Julian Posey (waiver claim from Cleveland), Antone Exum (sixth-round pick from Virginia Tech), Kendall James (sixth-round pick from Maine), Jabari Price (seventh-round pick from North Carolina)

Position coach: Jerry Gray (first season, hired to replace Woods)

Biggest issue: The Vikings are trying to shore up a secondary that was one of the league's worst against the pass last season, and while the addition of Munnerlyn, the health of Smith and the development of Rhodes should make them better, they've still got some depth questions to solve. They need to see if Robinson (or possibly Cox) can be an adequate third corner that allows Munnerlyn to slide inside on passing downs, and they need to find a safety to play alongside Smith from a group that includes Sanford, Sendejo, Blanton, Coleman and Raymond.

Player to watch: Robinson had an awful year in 2013, as the Vikings experimented with him at slot cornerback and a fractured sternum ended his season. He'll be back on the outside this season, and the Vikings hope he can become a reliable cover corner in Year 3. He could be asked to press receivers more often, which isn't the strength of his game, but he's got the speed and quickness to hang with the athletes he'll see on the outside. It's an important year for Robinson to prove he can do the job; otherwise, he might find his time with the Vikings is just about over.

Medical report: Sanford and Sendejo sat out most of the Vikings' spring program with minor injuries, but should be ready for training camp.

Help wanted: The Vikings have plenty of players to pick from, but the team saw up close last season how quickly injuries can decimate a secondary. This is a position where general manager Rick Spielman is likely always searching for depth.

Quotable: "The thing that Captain has done is, he is a smart guy, he has got some knowledge about things, but he's been very good in the slot," coach Mike Zimmer said. "He understands route concepts, he communicates well, so that part has been good to have him in there. If I can continue to get him to do what I want him to do then he is a calming factor."