The winless Bucs made the latest move during their bye week after general manager Mark Dominik contacted every other team in the NFL in an unsuccessful attempt to trade Freeman, a 4,000-yard passer a year ago and the team's career leader with 1,144 completions and 80 touchdowns.
Coach Greg Schiano benched Freeman after the 25-year-old completed just 45.7 per cent of his passes and posted a league-low quarterback rating of 59.3 through three games, all losses. Glennon made his first pro start last Sunday, turning the ball over three times during the fourth quarter of a 13-10 loss to Arizona.
"We appreciate his efforts over the past five seasons, but we felt this was in the best interests of both Josh and the Buccaneers," Dominik said a brief 33-word statement.
Freeman threw for 4,065 yards, 27 touchdowns and 17 interceptions in 2012, but his inconsistent play down the stretch contributed to the team losing five of six games and failing to make the playoffs for the fifth straight year. He led the Bucs to a 10-6 record -- though not a post-season berth -- while throwing for 25 TDs and just six interceptions in his first full season as a starter in 2010.
The release caps a tumultuous month in which Freeman overslept before missing a team photo shoot, was not voted a captain for time since his rookie year, and reportedly missed at least one other team meeting.
This week, the saga took a messy turn when Freeman released a statement through his agent, saying he had Attention Deficit Hyperactivity Disorder and entered the NFL substance-abuse program more than a year ago after mistakenly taking Ridilin instead of Adderall to treat the condition.
The NFL Players Association is investigating the quarterback's claim that someone in the Bucs organization leaked confidential information about him being in the program to the media.
According to Freeman and his agent Erik Burkhardt, the quarterback has passed all 46 tests administered by the league.
Freeman was declared inactive for last week's game and watched Glennon's debut from a suite at Raymond James Stadium. Schiano called it a "mutual decision."