It didn't take long into the offseason training program for him to figure out that the Lions' defensive line operates a little bit differently than some others he's been around in his nine NFL seasons.
"You have to be able to run to the ball," said the 6-foot-2, 310-pound Mosley, with a laugh, after a mini-camp practice last week.
It's one of the lasting footprints former Lions defensive end Kyle Vanden Bosch left on this unit.
The first practice Vanden Bosch suited up in for the Lions in 2010, he could be spotted running 40 yards down the field chasing ball carriers and trying to knock the ball out of their hands.
Soon, the entire Lions defensive line was doing it, and it's something they continue to do, even though Vanden Bosch is no longer on the team.
"Forty yards, that's all you count," Mosley said laughing. "Man, running everywhere."
But that's the manner with which the Lions want to play defense -- attack up the field and run to the football.
"His (Vanden Bosch) name is legend around the NFL," Mosley said. "All the coaches talk about him."
"This line can be as good as we want it to be," he said. "You see guys rubbing off on each other. Some guys are good in certain areas and guys are good in other areas and I think we'll be a good balance. I think we'll be an attacking, physical and ruthless defensive line.
"You've got (Ndamukong) Suh -- cat quick – and strong at the same time. Watching him and Nick (Fairley), all they want to do is get off the ball. We want to get our hands on people and we're really not caring where we end up, as long as we do our job and beat the guy that's in front of us. That's what it is."
Mosley joked that he's also getting used to being one of the little guys – in relative terms.
"Talk about length. Look, I'm tall, I'm 6-2, but these guys," said Mosley, referring to the Suh (6-4), Fairley (6-4),
"With length, you get an extra step. One regular step for them is two for me or somebody else. That extra length adds a lot more ground and space that you can cover and it's also hell for quarterbacks who try to throw the football with hands up."
Mosley's physicality seems to fit right in with how the Lions want to play defense upfront. He's learning how the Lions practice and want to play, and the way they rotate their defensive lineman, he'll be an important contributor.