The Florida Gators fielded two different teams with very different results in 2015.

The first, with Will Grier at quarterback, was one of the best in the nation, and went 6-0. The second, with Grier sidelined by a suspension for PEDs, was mediocre at best, going 4-4 and finishing on a three-game losing streak.

The Gators’ offense averaged barely 10 points in regulation time in their last seven games. The defense was good enough to beat Georgia, South Carolina, Vanderbilt and Florida Atlantic, but couldn’t hold up without offensive help against Florida State, Alabama and Michigan.

Quarterback play was the difference. With Grier, the Gators averaged 32.2 points per game, including 38 in a rout of Ole Miss. Without him, opponents stacked the box and forced 5-foot-10 backup Treon Harris to throw. The result was the Gators’ second-half collapse.

Suspended for a calendar year, Grier opted to leave Florida.

Coach Jim McElwain must overhaul the Gators offense in the offseason. There are holes to fill on the offensive line. Sophomore WR Antonio Callaway is the only proven playmaker.

But the first priority is finding a quarterback.

The Gators took a necessary step flipping four-star Floridian Feleipe Franks away from LSU. Much-traveled Luke Del Rio will be eligible. Purdue transfer Austin Appleby is another option. Three-star recruit Kyle Trask, a 6-5 1/2 pocket passer, is considered a project. Over two seasons, Harris has shown he’s not the solution, but could play in a pinch.

Franks enrolled early and will participate in spring drills. How quickly he adapts and learns the offense will be the key to Florida’s success in 2016.

“We’re excited about him and Kyle that are in here with that class as freshmen,” said McElwain on Wednesday. “Here is the great thing, at that position, too, is you’re getting an opportunity through these workouts right now to really kind of build a lot of — kind of see the leadership piece of it, too, as to how they go about their daily work. I know this: We are going to be able to complete some routes on air because these guys can throw it now.”

Del Rio may be the only other plausible option. But the son of NFL coach Jack Del Rio had no luck climbing the depth chart as a walk-on at Alabama and didn’t win the starting job at Oregon State, either. He could be adequate, but it’s hard to imagine him leading the Gators past Georgia, Tennessee or LSU.

“He’s a guy who kind of knows how to go about it,” McElwain told the Miami Herald of Del Rio’s work ethic and knowledge of the playbook. “He’ll be a guy obviously heavily in the mix. We’re sure excited he’s here.”

Appleby had a mediocre career at Purdue and lost his job to a freshman last season on a 2-10 team.

The 6-5 1/2 Franks is a potential game-changer. A drop-back passer with a strong arm and a commanding field presence, Franks is not a breakaway runner, but he is mobile enough to run when necessary.

If Franks provides a legitimate passing threat, the Gators should contend with Tennessee and Georgia for the SEC East title.

It would help if Jordan Cronkrite or Jordan Scarlett — sophomores and heralded recruits — stepped up to provide a running threat. And McElwain signed five receivers, including a trio of four-star recruits, to help get the passing game untracked.

Quarterback is the key. While Del Rio or Appleby could handle the duties, only Franks seems to have the ability to lift the Gators to the top of the division. Plus, he’ll be around for at least three seasons.