Raiders wide receiver Amari Cooper is a few days shy of his 23rd birthday, but it appears he’s coming of age for his third NFL season.

Raiders' Derek Carr on Amari Cooper: 'dog in him is coming out' (Heidi Fang/Las Vegas Review-Journal)

Oakland Raiders wide receiver Amari Cooper, center, stretches during an NFL football team activity Tuesday, May 23, 2017, in Alameda, Calif. (AP Photo/Eric Risberg)

Oakland Raiders wide receiver Amari Cooper (89) during day one of a mini-camp at the Raiders headquarters and training facility in Alameda, Calif. on Tuesday, June 13, 2017. Chase Stevens Las Vegas Review-Journal @csstevensphoto

ALAMEDA, Calif. — The first Amari Cooper casualty Tuesday was Sean Smith, as the Raiders’ wide receiver sprinted past the veteran cornerback on a deep Derek Carr pass in stride for a long touchdown.

Chuckle.

The second Cooper casualty was cornerback David Amerson. This time Carr trusted Cooper to wrangle a pass in traffic during a two-minute drill. Cooper did, high-pointing the football before falling onto the turf for a first down.

Snicker.

“Seeing him do it out here, we were just laughing, man,” Carr said after practice. “The guy has been going off all offseason. We were just laughing about how impressed we are.”

To the casual observer, Cooper has bulked up his physique since the end of the 2016 campaign. That change is obvious, one that can be measured with a tape measure. There is something else, though, that his quarterback sees in the third-year wide receiver.

It’s mental, and it’s become increasingly obvious in recent weeks.

“That dog in him is coming out,” Carr said. “That thing you saw at Alabama where he’d just take games over. Not to say that he hasn’t because he has, but I think it’s not just becoming a thing of, ‘What game is it going to be?’ It’s becoming a thing of, ‘That’s who he is.’ (Defensive backs) better know that he’s really taking it serious, that he’s trying to go attack them this year. He’s not going to let them come to him this year. That just comes with age.”

Cooper is still only 22; he turns 23 on Saturday.

He caught 83 passes for 1,153 yards and five touchdowns in 2016. The production came despite a modest finish; he totaled 31 receptions, 366 yards and three scores in the final eight games.

There’s been nothing modest about his performance this spring.

Contact reporter Michael Gehlken at mgehlken@reviewjournal.com. Follow @GehlkenNFL on Twitter.