TAMPA, Fla. —The people who sat in Williams-Brice Stadium on that December day three years ago surely went home marveling about Berkeley High’s quarterback, a water bug of a player who zipped through Northwestern’s defense for 191 yards and four touchdowns.

During warm-ups, the casual observer might not have noticed Bruce Ellington. He stood just 5-9 — easy to miss. But with run after run, Ellington’s presence grew larger and larger. And while Berkeley won the state championship and celebrated the conclusion of his prolific high school career, one person at the stadium was already pondering Ellington’s future.

Steve Spurrier Jr., who coaches South Carolina’s wide receivers, knew Ellington wasn’t a polished receiver. He hadn’t played the position full-time since his freshman year at Berkeley. But after seeing Ellington’s athleticism that day, Spurrier Jr. was certain Ellington would make a productive college receiver.

After a 2010 season in which Ellington didn’t play football and a 2011 season in which he played a minor role in USC’s offense, Ellington finally proved Spurrier Jr. correct in 2012. Entering Tuesday’s Outback Bowl against Michigan, he leads USC with 38 catches and 564 yards — two catches and 125 yards more than Ace Sanders, who has seven touchdown catches, one more than Ellington.

Ellington is no longer just an athlete playing receiver in the Southeastern Conference. He is a legitimate SEC receiver. He said he became especially comfortable with playing receiver at this level during the past two months. His stats support that notion. In the ninth game, Oct. 27 against Tennessee, he had six catches for 101 yards. In the next game, against Arkansas, he had five for 104. In the regular season finale at Clemson, he caught seven passes for 72 yards and touchdowns of 13 and six yards, the latter of which helped seal a 27-17 win with 4:17 remaining in the game.

“Last year, I was a little nervous, the first year of playing in the SEC,” he said. “But this year, I’m confident.”

That’s because he properly prepared for this season. In the summer of 2011, he wasn’t fully involved in football’s offseason workouts, as he split time with basketball. Last season, he caught 17 passes for 211 yards. Spurrier Jr. knew USC would need more from Ellington this season, because last year’s leading receiver, Alshon Jeffery, turned pro.

Spurrier Jr. said the gist of his offseason message to Ellington was: “If you’re going to start for this team, the rest of the team has got to know that you’re committed to this game, because too many people are working too hard to be here, that you’ve got to be working just as hard as they are.”

Ellington answered by pouring himself into offseason football workouts. He caught more passes, ran more routes and studied more film of defenses.

“Just getting the routine of playing football just made me more comfortable,” he said. “I kind of managed my time a lot better, getting ready for football.”

Sanders said Ellington “has become a complete football player.” But will he be one next season? Ellington said he hasn’t thought yet about if he wants to play football, basketball or both next year. He is currently doing both for the second straight season after playing only basketball as a freshman. With the way Ellington played this year, Sanders said there is no way he should quit football.

“He’s just learning the game inside and out now, from noticing coverages to knowing when the ball should be coming to him to knowing when he has to block this person,” Sanders said.

Spurrier Jr. said he hasn’t yet talked to Ellington about his 2013 plan. If Ellington does play football, he will have two seasons of eligibility remaining. Ellington is still rather inexperienced as a college receiver, and Spurrier Jr. said he will “be a lot better next year than he is right now.”

To hear USC head coach Steve Spurrier talk about Ellington, you get the impression that the Gamecocks’ coaches always believed Ellington’s current success was inevitable, as long as he just exposed himself more to football, the way he did in the summer.

“It was just a matter of time, him improving the way he has,” Spurrier said.