IRVING, Texas -- Cornerback Morris Claiborne played poorly last season, missed the entire preseason due to injuries and has said he will need a pain-killing shot to his right shoulder before playing in Sunday’s season opener.

What gives the Dallas Cowboys confidence in Claiborne?

“Well, he’s there,” defensive coordinator Rod Marinelli said. “He’s our starting corner. That’s the confidence. He’s gotta go do it.”

Quite a ringing endorsement for the sixth overall pick in the 2012 draft, right?

Marinelli isn’t the kind of coach who massages a player’s ego just for the sake of being polite. The fact is that Claiborne hasn’t done anything to merit much confidence since the Cowboys traded their top two picks for the right to move up eight spots to select him.

A sprained AC joint in his left shoulder impacted Claiborne’s performance all last season, forcing him to wear a harness and undergo offseason surgery. He’s recovering from the same injury to his right shoulder, although this isn’t as serious and won’t require Claiborne to wear a harness.

Claiborne, who essentially regained his starting job when Orlando Scandrick was suspended for four games, still must play through pain with a lot to prove.

“The challenge for him [is] to simply come back and be consistent, playing his position and all aspects of it,” coach Jason Garrett said. “Did a really good job recovering from an injury at the end of last season, and he had to deal with another one during training camp. He’s really worked hard to get himself healthy and ready to go.

“He has a chance to be a really good player for us and a complete player for us. Part of being a complete corner is being able to cover, play man, play zone, but also be a physical player at the line of scrimmage and as a tackler. We feel like he’s improved in that area, and hopefully this injury that he’s been dealing with doesn’t prevent him from being able to do that.”

As was the case last summer, Claiborne has downplayed concern about missing the entire preseason. He returned to practice last week and promised he’d be ready for Sunday’s season opener against the San Francisco 49ers.

“I’m not frustrated at all,” Claiborne said. “Where I’m at right now, I’m happy. I’m not upset at missing time or anything. I’m in a good place.”

That place is the starting lineup. It remains to be seen whether that’s good for the Cowboys.