"Mike's our starting quarterback from this point forward," Schiano said. "We're moving forward and Mike's our quarterback. That's the plan, and that's how we're going."
Schiano said he and general manager Mark Dominik "believe that this gives us the best chance to win today."
"We've lost eight of nine games and we haven't played particularly well on offense in the last nine games," Schiano said. "Although it's not completely the quarterback's fault, that position touches the ball every play."
Dominik told USA Today the Bucs haven't been contacted by any teams seeking a trade for Freeman.
The Bucs are making the change in part because they feel it is beneficial for Glennon with the bye week coming after Sunday's game against the Arizona Cardinals. Glennon can start this week, then have two weeks for coaches to review his performance and make adjustments before the Bucs play the Philadelphia Eagles on Oct. 13.
"It is beneficial, I think, that Mike will get to play a game and then have a bye week to really decipher through it and learn from the experience before he has to play his next game," Schiano said. "That's a side benefit of the decision. But it wasn't by any means the reason it was made now. We felt that it was time that Mike Glennon gave us the best chance to win, and that's why we did it."
There are five weeks until the trade deadline, and if a team loses a starting quarterback and has interest in Freeman, the Bucs are willing to trade him.
For now, he's their backup quarterback.
"This league is about finding a franchise quarterback, and with Josh's roller-coaster career, we don't feel he's that guy," a team source said.
Schiano said Monday that Freeman was still his starter even though he completed fewer than 50 percent of his passes during the Bucs' 0-3 start. On Wednesday, the coach moved to clarify those comments.
"After I met with [the media Monday], Mark and I spent a lot of time together and had some intense meetings trying to decide what's best for our football team," Schiano said. "We got with our ownership and we came to a conclusion as a group and made the decision organizationally that we were going to make a change at quarterback."
Tampa Bay selected the 6-foot-6, 225-pound Glennon in the third round (73rd overall) of the 2013 draft. He was the third quarterback taken in the draft and will become the third rookie to start a game at the position this season, joining the Buffalo Bills' EJ Manuel and the New York Jets' Geno Smith, the two quarterbacks picked before him. Manuel and Smith have started since Week 1.
"Mike's a smart, tough football player who loves the game," Schiano said. "I think he works extremely hard. I think he will go out and try to do what we're coaching him to do.
"He's not going to be perfect; no one is. But I think he's going to try to execute to the best of his abilities what we're asking him to do with the game plan. I think he'll be accurate, and I think he'll go out and do it."
Glennon said he was confident his time at NC State had prepared him for this opportunity.
"I have five years of an NFL-type offense under my belt," he said.
Freeman, a team captain the previous three seasons, was not elected as one this year. Schiano denied reports that he rigged the voting to keep Freeman from being selected and later revealed the quarterback had overslept and missed the team's annual photo session.
Freeman, drafted by the Bucs in the first round of the 2009 draft, is in the final season of his rookie contract. The team has said it was in no hurry to extend the deal.
Last season, Freeman threw for 4,065 yards and 27 touchdowns. (He is the franchise's leader in career TD passes with 80.) He has two touchdown passes and three interceptions this season.
Since his 10-6 season in 2010, Freeman is 11-23 (.324) as a starter. Among players with at least 20 starts over that span, only the Jacksonville Jaguars' Blaine Gabbert has a worse win percentage (5-20, .200), according to ESPN Stats & Information.
Freeman (17th overall) was the third of three quarterbacks selected in the first round in 2009, following top overall pick Matthew Stafford by the Detroit Lions and Mark Sanchez (No. 5) by the Jets. With Freeman's benching, only Stafford remains a starter.
ESPN.com Buccaneers reporter Pat Yasinskas contributed to this report.