Former Tennessee DL Daniel McCullers was selected by the Pittsburgh Steelers in the sixth round of the 2014 NFL Draft, but has failed to live up to expectations so far.

The 6-7, 350-pound lineman hasn’t seen the field much and hasn’t made much of an impact when he has played.

According to TribLive.com, Steelers defensive line coach John Mitchell said this season will be a pivotal one for McCullers, who is entering his fourth NFL campaign:

“Dan McCullers, he’s got to grow up,” Mitchell said. “It’s time to make a move right now. This is going to be his fourth year. And usually in this league, after about four years, you have got to make a move. Or, either, you move somewhere else.”

McCullers, to his credit, says he understands that the NFL is evolving and that defensive tackles must be able to put pressure on opposing quarterbacks, too:

“The big thing is be big — but also show you can move, be agile, make plays for the team and help them out,” he said.

“I have been a ‘nose’ all four years. But hopefully I can show my pass-rush moves and my little spin. I’m working on a little spin I can use. I’m gonna try to add that to it. So hopefully I can put that on film and put it out there so they can use me in that nickel situation.”

McCullers only has 1.5 sacks in three years in the NFL. He also only recorded 1.5 sacks during his two years in Knoxville.

He has appeared in 37 games in three professional seasons, including all 16 games last year.