LSU wide receiver Stephen Sullivan (10) makes the catch against Auburn defensive back Daniel Thomas (24) for a first down on fourth-and-7 to keep a last-gasp drive alive on Sept. 15 at Auburn. Sullivan's clutch grab from Joe Burrow gave LSU a first down, which led to Cole Tracy's 42-yard field goal on the final play in a 22-21 upset.

To know how far Stephen Sullivan has come in two-plus seasons of college football, all one has to do is look back at a seemingly routine 9-yard reception he made three weeks ago.

Routine in length, perhaps.

But it was incredibly huge when you consider the LSU football team wouldn’t still be undefeated and ranked fifth going into Saturday’s big game at Florida without that catch against Auburn.

Sullivan, a junior, flashed across the middle and cleanly plucked Joe Burrow’s tight spiral out of the air on a fourth-and-7 play that started at Auburn’s 48.

The clutch throw from Burrow to Sullivan, a rangy 6-foot-7, 232-pound wide receiver, kept LSU’s last-gasp drive alive.

Five plays later, Cole Tracy knocked through a 42-yard field goal on the final play of the game for a stunning 22-21 road victory against then-No. 7 Auburn.

In his first two seasons, Sullivan likely wouldn’t have earned the trust of the coaches or his quarterback in such a tight situation.

That was then, when Sullivan, a four-star recruit from Donaldsonville High School who was ranked as the No. 7 wide receiver in the 2016 recruiting class, caught just 11 passes for 219 yards and one touchdown — all in his sophomore season — in his first 21 games for LSU.

The Stephen Sullivan that burned Auburn is the one offensive coordinator Steve Ensminger and Burrow, LSU’s swashbuckling quarterback, have come to rely on as the Tigers continue to find their way as an offense.

In just five games this season, Sullivan has equaled his reception total of his first two seasons combined.

He has 11 catches for 143 yards, with seven of them producing first downs — including a 40-yard TD on the final play of the first half of a 31-0 rout of Southeastern Louisiana.

That catch, on Burrow's desperation heave into the end zone, came one week before Sullivan’s heroics at Auburn. Sullivan out-jumped several SLU defenders, cradled the ball to his body and fell to the turf despite having his helmet pop off.

At least part of Sullivan’s slow development can be attributed to playing behind experienced receivers like Travin Dural and Malachi Dupre as a freshman and DJ Chark and Russell Gage a year ago.

The other part is playing for two head coaches, three offensive coordinators and two position coaches in his first two seasons.

Finding the right spot for him and another towering receiver in Dee Anderson was another key to the equation, coach Ed Orgeron acknowledged Monday.

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“We have some big athletic receivers, and at the first of the year they weren’t getting open,” Orgeron said. “So we changed some things we're doing: More crossing routes, more mesh routes, more digs, more intermediate three-level routes, play-action pass.

“We finally got the receivers in the right spot; we’re finally doing the right plays to get the receivers open. I think that's the biggest improvement we're making.”

Sullivan, in particular, has bounced from position to position.

He was tried at the X and Z receiver spots and during preseason camp was moved to tight end for a couple of days because of a lack of depth there.

A grinning Orgeron remembered the experiment from early August and said, “That wasn’t really in his wheelhouse.”

So it was back to wide receiver, where Ensminger found Sullivan’s comfort zone.

“We moved him to the slot where he can catch the slant, or we can put him at X or Z where he can catch the short routes and then throw him the deep fade,” Orgeron said. “Those are some things he can do, so we’re moving him around.

“You know, you see an athlete like that, you want the ball in his hands, OK?”

All-American cornerback Greedy Williams said he can see a difference going against Sullivan every day in practice.

“Stephen doesn’t say much, but when he gets on that field he’s a different guy as far as going out and making big plays,” Williams said. “He plays his role, and that’s to come in and make big plays for us.”

Burrow certainly likes what he’s seen of Sullivan, who was shut out in the season opener against Miami but had two catches each against SLU, Auburn and Louisiana Tech.

Then he had a career-high five receptions for 50 yards — three more than his previous high — in Saturday night’s rout of Ole Miss.

“I feel like Stephen’s more aggressive this year than last year,” said Justin Jefferson, LSU’s leading receiver with 18 receptions for 294 yards and two TDs. “He's making bigger plays than he did last year.

"I feel like the coaching staff is trying to give him opportunities to go out there and make those big plays we’ve been talking about.”

Burrow agreed.

“He’s become a real big target for us,” he said. “I always know where he is on third down, where I can find him. He’s really making a lot of plays for us.”

On fourth down, too.

Follow Sheldon Mickles on Twitter, @MicklesAdvocate.