BEREA, Ohio -- Browns safety Donte Whitner is known to lay the wood on opposing receivers, and he did so verbally on Cleveland's No. 8 overall pick from May's draft.

Whitner told ESPN that cornerback Justin Gilbert needs to "stop being a kid" after the rookie struggled for much of the season and saw his playing time dwindle to players with limited to no experience Sunday at Carolina.

Gilbert played 17 snaps Sunday, less than special teams ace/corner Jordan Poyer and fourth-round rookie Pierre Desir, who didn't log a defensive down through the first 14 weeks of the season.

Browns rookie Justin Gilbert needs to "grow up and not be a kid anymore," his teammate said. Jason Miller/Getty Images

"It's time to grow up and not be a kid anymore. It's a wasted year for him," Whitner said. "There were so many ups, so many downs -- a lot of it has been brought on by himself. He has to look himself in the mirror like Karlos [Dansby] said, he has to understand what he did wrong, what he needs to get better at, and make sure that you're back here working out from day one when we return here to show everybody you have a good attitude and you want to go out there and be the player they drafted you to be."

Dansby told reporters Monday that Gilbert has to make a transition as a young player at a difficult position but he must "look in the mirror" to do so.

Coach Mike Pettine said Gilbert did not break a team rule but had some on- and off-field issues that led to his diminished play Sunday.

Gilbert didn't beat out veteran Buster Skrine for the starting outside cornerback spot during training camp, and undrafted rookie K'Waun Williams won the starting nickel job, relegating Gilbert to the fourth corner spot. Gilbert has flashed potential, including an athletic 23-yard interception return for a touchdown against Indianapolis in Week 14. Gilbert was in the Browns' locker room for the early portion of media availability Tuesday but was not available after Whitner made the comments.

Asked whether Gilbert's issues stretch beyond the normal rookie transitions, Whitner said, "Yeah, but you know we keep all that in house."

"He has things he needs to improve on and grow up in," Whitner said. "Stop being a kid."

Gilbert has admitted the Browns' man-coverage scheme was foreign to him. He played off athleticism instead of technique.

Does he want to change?

"I think he wants to do that but only time will tell," Whitner said.