The easy smile seemed to show he had moved on after feeling compelled to tell ''the haters out there your opinion doesn't matter so keep it to yourself.''
Moving on is what cornerbacks get paid to do, even those playing with an injured shoulder, wounded pride and the burden of being a No. 6 overall pick that the Cowboys moved up eight spots to get a year ago.
Claiborne still thinks he made the right move coming over the back of Chiefs receiver Donnie Avery to break up a pass short of the first down on third-and-10 - even if Cowboys coach Jason Garrett joined the chorus of those saying he was a little too aggressive.
And even if the resulting first down eventually left Tony Romo more than 50 yards from field goal range with 16 seconds left in Kansas City's 17-16 win.
''Ain't thinking about it,'' Claiborne said Wednesday after the first practice for Sunday's home game against St. Louis. ''It's nothing to me. I'm a corner. I learn to let stuff go quickly.''
It's not the first lesson in moving on for the former All-America from LSU.
Last year in Philadelphia, Claiborne got beat for a touchdown and was penalized three times - twice for defensive holding and once for interference.
Garrett says Claiborne impressed everyone with the way he kept playing in that game, and moved on after a 38-23 Dallas win.
But there is a troubling stat for Claiborne: In eight games since that day in Philadelphia, he doesn't have an interception and didn't even have a pass breakup in seven of them. He's up to 17 career games, with just one interception.
Thus, the scrutiny when the glare of the spotlight turned negative again in Kansas City.
''I could care less what somebody else says,'' Claiborne said. ''As long as I'm not hearing nothing from my coaches or the owner, I don't really care.''
Garrett doesn't sound worried about him.
''The opposing offenses are going to have success against corners in this league,'' the coach said. ''The quarterbacks are too good, the receivers are too good and it's your job to keep bringing it when you play those kinds of positions.
''They might have some success, but you're not going away and I think Mo has demonstrated that throughout his career.''
The bigger concern for Claiborne might be his left shoulder. It was dislocated in the opener against the New York Giants, and he kept playing after trainers popped it back into place.
To try to protect the shoulder, Claiborne was limited to nickel situations against the Chiefs, with Orlando Scandrick taking his regular spot.
Even then, Claiborne ended up one-on-one in the open field and fell to the ground in pain trying to make a tackle early in the game. He kept playing, and was in for more than half the defensive snaps.
Claiborne said he did more in practice Wednesday than he had last week - an indication he might be ready for something closer to full-time duty.
''Even though it's hurting, I kind of tell myself it's not hurting, it's not hurting, it's not hurting,'' said Claiborne, who missed all the preseason games after jamming his left knee in training camp.
''A couple of times I believed myself, but a couple of times I didn't. Just try to keep it on that side where I believe it, and I'll deal with the consequences later on.''
Before injuring his knee in camp, Claiborne did his best to hide a dislocated pinkie that a trainer popped back into place.
His biggest priority in the offseason was getting stronger, and the dividends looked as if they were paying off the first two weeks in California.
Now Claiborne's not even sure the pain will go away this season - and there are still 14 games left.
''He's used to feeling good, feeling fresh, feeling athletic, and it's hard when you've got an ailment,'' safety Will Allen said. ''I'll continue to talk to him, continue to motivate him. We're going to need him.''
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