The transition was supposed to be seamless.
Those were big shoes to fill, but most assumed two of the most touted recruits in recent years would keep the programs humming in the chase for national championships.
Four losses later, Texas (3-2) is out of the Top 25 for the first time in a decade and the No. 22 Gators (4-2) are fading.
What went wrong?
Both programs are struggling to adjust their offenses to pro-style passing quarterbacks after years of Tebow and McCoy beating opponents with their legs as much as their arms. Both teams now rank in the bottom half nationally in total offense.
Texas tried to rebuild its offense around Gilbert with a power running game and play-action passing. Florida has tried to put Brantley in the spread-option that Tebow ran to near perfection.
Both teams have lost two in a row, scoring is down and fans are getting frustrated.
The Longhorns won 19 in a row from 2004-2005 and a national championship with the elusive Vince Young running the zone read. Then came McCoy, who dipped and dashed around the pocket and into defensive backfields for four years. The skinny, small-town McCoy, who many considered an afterthought recruit in 2005, played with a "prove-you-wrong" chip on his shoulder.
Texas recruited Gilbert, a high-school All-American and son of former NFL quarterback Gale Gilbert, knowing that changes would have to be made.
You don't pass on a talent like Gilbert just because he's different than the previous guy, said Greg Davis, the Texas offensive coordinator.
"It wasn't a big, long philosophical conversation. It was, 'Hey, we think this guy's real good, let's recruit him,'" Davis said. "We don't ever want to box ourselves into a philosophical position. We want to always be able to do what our players can do ... the change is your quarterback and what can he do."
The new offense has been a failure so far. The running game ranks No. 82 in the country and Gilbert has yet to find a reliable go-to receiver. Texas has scored three or fewer touchdowns in three games this season and Gilbert has five interceptions to go with his four touchdown passes.
Davis admits he has limited Gilbert's options to throw downfield, often calling shorter routes early in games to help Gilbert find his rhythm.
Gilbert went 39-4 as a starter in high school with a 30-game winning streak and two Texas state championships. If Texas loses at No. 5 Nebraska on Saturday, he'll have Texas' first three-game losing streak since the end of the 1999 season.
Texas had an off week after the loss to Oklahoma. Gilbert said he tried to get away from football for a few days. He played a few rounds of golf with his dad to clear his head.
"I think Garrett is fine," Texas coach Mack Brown said. "He's smart. He's tough. He grew up in football and he understands that at Texas, you need to win games.
"He understands that he is going to be scrutinized as the quarterback. We told him that before he came here ... He does want to continue to win like the great quarterbacks before him, and that is something that's on my plate. It's on his plate. It's on Greg Davis' plate. All of us need to pick it up," Brown said.
At Florida, Brantley is struggling while coach Urban Meyer asks him to do what Tebow did.
Tebow, a larger-than-life leader in the huddle and the locker room, was savvy in the spread-option and could pummel defenders with his size when he ran. When Brantley runs the option, the result is awkward at best.
The running and poor pass protection have taken a physical toll, leaving Brantley playing with sprained thumb and sore ribs. The rib problem forced him to change his throwing motion, resulting in a sore shoulder.
"He's a tough guy and played really tough" in last week's loss to LSU, Meyer said. "That really showed us a lot about who Johnny is."
Meyer laments a "lack of explosive plays" in his offense. Brantley's longest pass of the season covered 51 yards, but that came on a short route against a blitz the receiver turned into a big gain.
"We're not hitting the home run shots," Meyer said.
Meyer has refused to tweak the offense to fit Brantley's passing strengths, and said last week the option is "who we are" and "that won't change."
Brantley says he's fine with that.
"That's what our offense is," Brantley said. "It's been successful for us these last four years so why not keep doing it?"
AP Sports Writer Mark Long contributed to this report from Gainesville, Fla.