It was a cruel twist to a promising career.
Darius Fleming joined teammates at the 49ers rookie camp last May and went down with a season-ending injury a short while after the workout began.
"It wasn't what I wanted," said Fleming, a fifth-round draft pick in the 2012 NFL Draft. "It wasn't what I expected."
The former Notre Dame linebacker suffered a severe injury to his left knee. It was the first major injury suffered by the Chicago native and a frustrating experience for the Fighting Irish's 2011 Lineman of the Year.
Looking back on it, Fleming is grateful that the 49ers organization kept his morale high by keeping him on the physically unable to perform list. Fleming traveled to all of San Francisco's home and away games. He was also a mainstay in the meeting rooms with his fellow linebackers.
"They kept me here and I was able to learn," Fleming said prior to the start of San Francisco's offseason football school "I've never dealt with anything that severe, but I was able to handle it with the support from the guys."
The No. 165 overall selection in the 2011 draft has rehabbed vigorously ever since the setback. The dedication paid off. He's returned to the field for the 49ers offseason program.
The 6-foot-2, 255-pound linebacker is eager to carve out a role on special teams this upcoming season. Fleming hasn't played on special teams since his sophomore year at Notre Dame, but feels that learning Brad Seely's system will be his best chance of helping the 49ers in 2013.
"I know that'll be how I impact the game so I'm looking forward to every bit of it," Fleming said.
A team-first attitude isn't new to Fleming. He stood out last year as a team-oriented player during the hardship he encountered early into his professional career with the 49ers.
Instead of sulking about his situation and letting the injury linger, Fleming vowed to make the most it. He wanted to bounce-back better than ever and learn the ins and outs of Vic Fangio's defense before being able to play in 2013.
"I think that's going to help me going into this year, knowing the plays," Fleming explained. "I haven't done them physically yet, but knowing the plays, it'll help me when I'm out there meshing with the guys."
Fleming meshed with his teammates without playing on the field with them last season. He had former Irish teammate and college roommate Ian Williams on his side to keep morale high. In addition, Fleming bonded with fellow rookies and served as an extra set of eyes for them.
"He always had a positive attitude and was looking to contribute any way he could," said outside linebacker Cam Johnson, last year's seventh-round selection out of Virginia.
"If he saw something on the field he would try to help you with it," Johnson continued. "If you had trouble with a play, he'd try and help you with it."
Still, Fleming was troubled from not being able to produce with his teammates. The injury served as motivation for the former fifth-round pick. It also was a blessing in disguise.
Fleming is better prepared for the NFL.
"I haven't been through it, but I've seen it," he said. "I know what to expect so it won't be a shock for me. That's definitely an upper-hand. I'm still a rookie, but at the same time, I'm not.
"It'll help me produce this offseason."
Fleming feels ready for San Francisco's Organized Team Activities and the challenge of competing for a role on a talented roster. He looks back on the injury with appreciation for the support he received and knows not to take precious opportunities for granted.
"I'm back," Fleming said. "I feel great, I feel like everything is in tip-top shape. I'm enjoying every bit of it and looking forward as we continue to build on what we're doing.
"I'm not worried about my body at all."
Fleming is back working alongside veterans in the offseason program and it's been a rewarding experience. Last May, Fleming only saw a brief portion of the team's rookie minicamp. He never actually practiced with veterans.
The experience this time around makes all the rehab worth it.
"It's everything I thought it would be."