Donnie Alexander really did think his opportunity to play at LSU had passed.

He thought it was gone when his first career start — at Syracuse his sophomore season in 2015 — lasted just three plays.

After that game, he sat slumped over in the Carrier Dome’s visiting locker room, frustration brewing inside of him, his mouth shut and his demeanor normal, as not to expose his feelings to teammates and coaches.

“That was probably one of the moments where I was like, ‘Dang. I had my chance,’ ” Alexander said earlier this spring. “It was so quick, and I didn’t really get to do as much as I thought I was going to be able to do.

“I was pretty down about it,” he continued. “I’m not the type of person to sit there and complain and whine about the situation. I just tried to step up whenever my chance came.”

The greatest chance of his college career is here. It’s now. Not exactly right now, as he’s currently recovering from last week’s shoulder surgery. But it’s now, as in this year — his final one at LSU.

He knows this, too. Everyone does. It’s Donnie’s year. His time, they say. He can continue the tradition of first-year starting senior linebackers breaking out in their final season, then heading to the NFL draft. He hopes to follow Deion Jones (2015) and Duke Riley (2016), virtually unknown before they became some of the Southeastern Conference’s most productive players.

Jones and Riley combined for two starts before their senior seasons. Alexander has three, having filled in for an injured Kendell Beckwith in the final two games of last season.

In just a few months, Alexander went from reserve junior to the most experienced inside linebacker on LSU’s team, the senior leader who’s expected to serve as LSU’s man in the middle this fall at the Mack position. He never thought the day would come.

“There were a few tough moments in my career where I felt like I probably wouldn’t ever get my chance,” he said. “Now that it’s here, everything that happened before me, happened for a reason.”

You won’t see Alexander next Saturday during LSU’s spring game, as he continues recovery from surgery. Doctors surgically repaired a torn labrum in his right shoulder, an old high school injury he re-aggravated last season.

Surgery “went beautifully,” said Norman Randall, Alexander’s position coach at Edna Karr for three years. “He’s on track.”

Surgery for a torn labrum — the cup-shaped rim of cartilage reinforcing the ball-and-socket joint of the shoulder — is a somewhat speedy process. In fact, guard Will Clapp underwent a similar procedure in mid-January. He began practicing, in a limited role, 10 weeks later.

By the time preseason camp rolls around in August, Alexander expects to be healthy. He’ll be poised to take over for Beckwith and play alongside fellow new starter Devin White — both of them leading a young position group that will include signees Tyler Taylor and Jacob Phillips, arguably the best signee duo of inside linebackers in 2017.

Alexander hopes, by August, that he’ll weigh 227 pounds — about 10 pounds heavier than he was while participating in the first 12 spring practices. The New Orleans native played at 215 last season and knows he must bulk up to be a middle linebacker in the nation’s most physical conference.

Gaining weight, though, is not so easy for such an active 21-year-old.

He recently received a meal plan from LSU’s nutritionist.

“She sat down with me and talked to me about how many calories I need to eat every day because I burn so much calories at practice,” Alexander said.

An average adult male eats about 2,000-2,500 calories a day. Alexander’s daily calorie goal is 5,000.

Gaining weight was an issue for Alexander in high school, too. In fact, coaches during the offseason kept gallons of chocolate milk in the locker room fridge “personally for him,” Randall laughed. During camp, they fed him “three to four” peanut butter and jelly sandwiches before and after practices.

His meal plan at LSU includes five meals a day. He doesn’t really count his calories. “I just stuff myself,” he smiled.

Like, for instance, when he eats at LSU’s dining hall, The 5.

“If they have spaghetti, I get two plates and try to throw a salad in there,” he said. “I get to my apartment and will eat some more noodles or a pizza.”

Such is life for Alexander as he continues to make the transition to the middle linebacker spot. He played safety and outside linebacker in high school at Edna Karr after moving from the quarterback position.

That’s right — Alexander played quarterback for the first five practices of spring during his ninth-grade season at Karr before coaches moved him to defense. Brice Brown, Karr’s head coach, doesn’t remember Alexander as a quarterback. He remembers him as one of the hardest workers he’s ever had.

“Overachiever,” Brown said. “It’s really paying off now at LSU.”

Alexander manned the strongside linebacker position under defensive coordinators John Chavis and Kevin Steele. He credits Steele for help with his transition to the inside.

“Coach Steele said I had good instincts, but I would try to react faster than what I should,” Alexander said, touching on an issue that plagues young players who move from outside to inside linebacker. “He tried to slow down the game. He showed me how to read from the running back to the (offensive) line. That added a lot to my game.”

Steele gave Alexander that first career start at Syracuse — the one he’d like to forget.

Alexander started in place of Jones, who was suspended for the first half of that game for a targeting penalty the previous week. Alexander saw three snaps before coaches inserted Riley.

“It was pretty brief,” Alexander laughs about it now. “It was a humbling situation.”

On two of his three plays, a Syracuse offensive lineman blocked Alexander out of the play completely. On the third, he showed some indecisiveness in coverage that resulted in a complete pass. Out came Alexander, and in came Riley.

He admits that transferring from LSU was “always in the back of my mind,” but he stuck it out — just like Riley and Jones — and is poised to take his rightful place in the linebacker lineage.

And it’s a good thing he saw that start at Syracuse, despite its brevity.

Afterward, he told Randall that the speed of the game — the difference between practice and live action — affected him most of all.

Said Randall: “I told him, ‘It’s good you got to jump in the fire. Now you are prepared for those moments.' "

Down the stretch

LSU conducts its final week of spring drills this coming week, capped off by the spring game.

  • Tuesday: Regular full-pad practice
  • Thursday: Student Appreciation Day (students can attend a light practice at Tiger Stadium)
  • Saturday: Spring game (7 p.m. Tiger Stadium)

Follow Ross Dellenger on Twitter, @RossDellenger.