He was thrust into the starting lineup as a rookie, then benched and injured in his second season. While trying to learn all the nuances of one of the toughest positions in team sports, he went through three offensive systems and four different position coaches.
As a result, his bright spots have been few and far between.
Now, entering his third season, Gabbert is down to his final shot at becoming the team's franchise quarterback.
Gabbert and Chad Henne are in an open competition for the starting job, and it's unclear whether the loser will even make the 53-man roster in the fall.
"I view it as an opportunity," Gabbert said Wednesday, the second of a three-day voluntary minicamp for veterans. "Everybody's got to go out there and prove themselves year-in and year-out. In the NFL, there's always somebody looking to take your job."
In Jacksonville, most fans and even some teammates are ready to see someone take Gabbert's job.
It could be Henne, the former Miami Dolphins starter who signed a two-year contract with Jacksonville in March 2012.
"The only thing you can ask for as a professional athlete is competition," Henne said. "It's only going to make you better. There's going to be a lot of pressure. But if you're a quarterback, you want that pressure because there's pressure on you at all times. I think that's what makes us grow and become great quarterbacks."
Henne started the final six games last season after providing an offensive spark off the bench against Houston in November. The former regime seemed committed to Henne, but then coach Mike Mularkey and his assistants were fired after the worst season in franchise history.
New general manager Dave Caldwell and coach Gus Bradley gave neither quarterback a head start in the competition, even saying they plan to bring in another signal caller before training camp.
The Jaguars explored trading for Seattle backup Matt Flynn, who ended up in Oakland. They're now likely to pick a quarterback in the second or third round of next week's NFL draft.
"Well, we have two quarterbacks on the roster, so we know we have to have more going into camp," Gabbert said. "Honestly, you can't worry about that. We're pretty individually motivated to go out there and play a little football. ... All you can worry about as a player is the things you can control, and that's how you prepare, how you study, how you practice, how you eat, how you sleep, just little things like that.
"If you accomplish that on a daily basis, you can sleep well at night."
The Jaguars haven't played well since trading up to get Gabbert with the 10th overall pick in the 2011 draft. Eight teams with apparent quarterback needs passed on the former Missouri standout, but former Jaguars general manager Gene Smith gambled on the two-year starter who played in a spread offense and worked mostly from the shotgun formation.
The choice eventually doomed Smith as well as former coaches Jack Del Rio and Mike Mularkey.
In 15 games as a rookie, Gabbert completed 50.8 percent of his passes for 2,214 yards, with 12 touchdowns and 11 interceptions.
He was supposed to be considerably better last season, after the team brought in an entirely new offensive staff. But improvements were slight as his inconsistency continued. Gabbert completed 58 percent of his passes for 1,662 yards, with nine TDs and six INTs in 10 games.
He was benched the day before it was revealed he would miss the final six games with an injured right forearm. He also had surgery to repair a torn labrum in his left, non-throwing shoulder.
He recovered in time for minicamp -- and to learn a third offense in as many seasons.
"It's a new year, a new mindset, new team, that's the kind of the way we're viewing things," Gabbert said. "There are challenges every year regardless of the situation and you've got to go out there and prove yourself regardless if you have a new coaching staff or whatnot.
"You have to go out there and play at a high level and prove to people you can still play in the National Football League."
The only ones who really matter now are his coaches, who have the final say on his final shot in Jacksonville.
"I appreciate what the fans want to hear right now, but we've had one practice and we've had whatever amount of meetings -- seven?" offensive coordinator Jeff Fisch said. "We have two guys competing as hard as the possibly can to put themselves in position to be the starting quarterback. I think they need to have tunnel vision. I think they need to focus on what they can control and not focus on really anything other than that."