"We needed to create a roster spot, and that's really what it came down to," Mangini said.
Smith's agent, Neil Schwartz, said his client called him Saturday to inform him about the release.
The 6-foot-2, 325-pound Smith, who can play end or nose tackle, was one of the Browns' most vocal players -- on and off the field. He played two seasons with Cleveland after signing as a free agent in 2007, and he made nine starts last season, finishing with 47 tackles in 11 games.
But Smith's biggest moment might have been his confrontation with Quinn last December. Smith reportedly punched Quinn, who at the time was sidelined with a season-ending finger injury, in the face following a heated argument.
Mangini was asked if he found Smith to be disruptive.
"I think Shaun did a good job while he was here, and in terms of his experience prior to me getting here, I wasn't familiar with all of those things," said Mangini, who was hired in January after Romeo Crennel was fired.
Browns defensive end Robaire Smith wasn't surprised by his teammate's release and didn't want to speculate on whether it was a message from Mangini.
"Anytime you lose a teammate, a friend, it's going to hurt a little bit when they're gone, but it's something that goes on upstairs," Robaire Smith said. "I'm quite sure he knows the business. I don't know what was going on. That was a coach's decision. You'll have to ask coach Mangini."
A nine-year NFL veteran, Robaire Smith knows that one day the business side of football likely will catch up to him, too.
"It's a new regime and there's a lot of different things, a team headed in a different way, so there's always a possibility anybody could be gone," he said. "Maybe you thought you was doing good and you weren't doing what they (coaches) want. It's a business. If you're here, you're here, and that's why every time you play you've got to put something on film for the other 31 teams."
After taking the job, Mangini didn't individually met with players for several weeks because he said he wanted to find out more about them.
"I wanted to be able to watch the tape, make sure I did my due diligence in terms of learning about the players and then be able to sit down with them and give them an honest assessment of where they were, what expectations were," Mangini said. "I never like to just jump in, say something and then have to go back and backtrack."
Cleveland's coaching staff had asked Shaun Smith to drop weight before training camp, and last week he reported lighter than he had been in years. He signed a four-year free-agent contract worth $8.6 million in 2007 after playing two seasons with the Cincinnati Bengals.
Also, Mangini offered no update on injured offensive lineman Rex Hadnot, who was carted off the field Thursday with what appeared to be a serious knee injury. Hadnot was engaged in a block when he was hit on the side of the knee by rookie linebacker David Veikune, who was blocked into him.
"Injuries aren't anything I'm going to talk about," Mangini said.
Copyright 2009 by The Associated Press