The announcement came a week after Beamer had said that Glennon would be the starter while Taylor redshirted, and a few days after the then-No. 17 Hokies lost their season opener to East Carolina 27-22. Virginia Tech was not ranked in The Associated Press Top 25 poll this week.
Taylor is more mobile than Glennon, a drop-back passer, and Beamer said his inexperienced team needs help with its running game.
"Putting another guy in the game that can help you run the football is in our best interests," he said. "I don't think with young receivers you want to rely on throwing the football 40 times a game."
The inexperienced defense is not as good as it has been in the past, Beamer said, and while the offensive line is better than it was a year ago, "we still have trouble holding up at times."
Beamer would not say which quarterback will start Saturday at home against Football Championship Subdivision Furman, nor would he give any details about how they will be used.
Glennon and Taylor were not available for interviews, and other players said they had not heard of the change before Tuesday's announcement.
Offensive tackle Ed Wang said he was surprised, but he also was surprised when Glennon was named the starter because the team had practiced with two quarterbacks.
"Those guys feed off each other," said tailback Kenny Lewis Jr. "They play to their peak performance when both of them are in there."
Beamer stressed that the decision was not a reflection on Glennon's performance against the Pirates, when the fifth-year senior completed 14 of 23 passes for 139 yards and was intercepted twice.
"I'm very hopeful Sean will have an NFL career," Beamer said. "That tells you what we think about him and his talents."
Beamer said Glennon was disappointed, but the news may have had a familiar ring. Glennon also lost the starting job last year, but it came after two games instead of one.
He was replaced by Taylor after a slow start and a 48-7 loss at LSU, but reclaimed the job after he stepped up and played well when Taylor was injured midway through the season. Glennon was named MVP in the Atlantic Coast Conference championship game, where he was 18-of-27 for 174 yards with three TD passes against Boston College.