Now, the defensive back is looking to prove the Lions made a good decision as he contends for a job at the CFL club's training camp.
"(The injury) has been a good learning curve, and it's made me a better professional, I believe, because I know I can't control anything else," said Walker. "I have to control myself. And, I controlled my rehab, and I worked hard at it — and I'm here today."
But to stick with the Lions, he will have to master an unfamiliar position quickly. The 21-year-old Vernon, B.C., native is in contention for a job at safety as the Lions look to replace Cauchy Muamba, who bolted to the Winnipeg Blue Bombers as a free agent in the off-season.
"When you look at our needs and the potential for the conversion to happen for him, I look at him as a free safety," said Lions coach Mike Benevides. "When you look at his speed and when you look at his heart and skill set, how he plays with a physical edge, that's where he has the best opportunity to compete."
Before transferring to UBC, Walker played on offence in two seasons with the University of Saskatchewan Huskies and his former Okanagan Sun junior team. At UBC, he briefly played defensive halfback.
"I've only played three games at safety in junior and two games at defensive halfback (with UBC)," said Walker, who also played an exhibition game with the Thunderbirds.
"But I used to play quarterback and slotback. When I was running a (pass route), I'd always be watching the safety to see what my read was going to be to beat the offence."
Recalling his days on offence, Walker tries to go to the spots where he knows the receiver does not want the safety to be. But Benevides said Walker will also have to prove that he can earn a spot on special teams.
Muamba also played special teams, and the Lions need to fill another hole on kicking units following James Yurichuk's departure to the Toronto Argonauts as a free agent.
Benevides has been impressed with what he has seen of Walker on the field thus far. The coach also liked the way he battled back from an injury that threatened his CFL career before it got started.
"There's a lot to be said for him fighting through a devastating knee injury," said Benevides. "He's done everything he has to (in order) to try and get an opportunity to be here."
Walker was injured in the Thunderbirds' season-opener against the Manitoba Bisons and spent several months recovering. He still managed to get healthy in time for all necessary CFL combine and Lions tryout camps as well as several other informal workouts that B.C. defensive backs coach Mark Washington put him through in advance of the draft.
Used to going all out at everything, Walker struggled not to do too much too soon during the rehabilitation process.
"You really have to stay in your shoes, because if you don't and you do something dumb, then you're going to miss your whole shot," said Walker.
After watching him succeed in his recovery quest, the Lions provided a new one by drafting him in the sixth round, 50th overall.
"When the opportunity came, we wanted more depth at the free safety position," said Benevides. "So (Walker) was a perfect pick ... ."
Walker is in line for a backup role to Muamba's anticipated replacement. J.R. LaRose, entering his fourth year with the Lions and eighth in the CFL, has the starter's job for now, pending his performance in exhibition games in Calgary and at home against Edmonton before season opener against the Stampeders on June 28 back at McMahon Stadium.
In addition to his desire and determination, the Lions like Walker's passport. The starting and backup safety spots are ticketed for Canadians as the team manages the nuances of the CFL's import and non-import ratio.
Benevides said Walker also has a good chance to earn a spot because CFL teams are expanding their practice rosters to nine players from seven this season. The two extra spots must be filled by non-imports in accordance with the league's effort to develop more Canadian talent.
If Walker does not stay with the Lions, he could return to UBC, where he has three years of collegiate eligibility remaining. But he is not overly keen on returning to the classroom, preferring instead to pursue his CFL dream after overcoming significant adversity.
"I'm making sure I'm prepared to be a starter one day," he said.
Notes: Centre Angus Reid remained out with a sore back Tuesday. He went to get examined by a specialist. … Offensive linemen Cameron Thorn (concussion) and Andre Ramsey, who underwent arthroscopic knee surgery, are sidelined indefinitely with injuries suffered in camp.