Linebackers coach Steve Russ recalled an old saying when he spoke to the media Aug. 4: you don't know if you're going to get an opportunity, but you had better be prepared. That's the same attitude Reuben Foster has had for the past 15 months.

There has been little news on Foster since he tore his ACL and LCL during OTAs last May. The team placed him on the Physically Unable to Perform List prior to training camp, but head coach Ron Rivera said he is confident in the progress Foster has made towards a comeback.

The coaching staff needs to see how Foster looks on the field before placing him on the active roster, but at least from a mental standpoint, it seems like Foster is ready to go.

"Reuben has been fantastic," Russ said. "He's back there taking mental reps. He's making the calls. He's lining up. He's putting himself in that position."

Foster was clearly worthy of the first-round pick San Francisco used on him in 2017. He had 211 tackles and seven sacks in three seasons at the University of Alabama, and according to Pro Football Focus, he led all FBS linebackers in run-stop percentage for the 2016 season. PFF even compared him to seven-time Pro Bowler Patrick Willis.

"High praise, but it's a reflection on Foster's ability to do everything," PFF wrote in Foster's scouting report. "He has the top-end athleticism that Willis had, which allows him to play sideline-to-sideline and cover running backs, tight ends and slot receivers, as well as the strength and physicality needed to consistently take on and beat blocks on inside runs."

Washington expected Foster to bring a spark to a defense that finished the 2018 season 15th in points allowed when they claimed him off waivers, but his ligament tears suffered on the first day of 2019 OTAs halted those plans. It has been nearly 22 months since Foster has played in a game.

Foster has spent most of his time recovering and rehabbing, but the work he has put in over the course of the past year is obvious to Rivera and the new coaching staff.

"He's done a great job...when I was able to see him," Rivera said in April. "It looked good, it looked like he was working his way back."

The team will monitor Foster's progress before they decide to take him off the PUP list, but Russ believes in teaching and interacting with players as if they will be on the field. Russ said his job is to make sure his players know their assignments, so he's doing everything he can to make sure Foster is "ready mentally and emotionally to go out there and play football."

It also helps that Russ can see Foster paying attention during Zoom meetings. In fact, he will mute himself whenever Russ tries to quiz one of his teammates so that he can practice making the calls.

"I told him, 'I don't have to ask you a question for you to be able to answer it,'" Russ said. "And I really like where Reuben is, I like his intent. I really like his focus. I like his discipline right now."

Russ cannot speak on Foster's recovery process -- "I'm not a trainer," he reminded the media -- but he did say there's "no doubt" Foster would be a fun player to work with. He led the 49ers' linebacker corps during his rookie season with 72 tackles -- good enough for second-most on the team -- and PFF gave his 2017 performance an overall grade of 81.2.

Still, Foster's status on the team will ultimately come down to what he can do on the field. When asked what he thinks about Foster's progress, Russ said, "The physical part will come through reps and obviously with great work with [head athletic trainer Ryan Vermillion] and the trainers and [head strength and conditioning coach] Chad [Englehart]] and the strength staff. ...But my job is to make sure that he is ready when he hits that field."

That's why it is so critical for Foster to make positive strides in the coming weeks. Rivera said when Foster and Alex Smith were placed on the PUP list in July that he thinks both of them have had good offseasons, but he wants to see "actual football movement" before they're cleared.

"You really don't know until you get them out on the field pounding and doing football specific drills," Rivera said. "Then we've got to see how their injuries react."

Even if Foster is cleared during training camp, he will still need to compete with the other linebackers on the roster. He's getting closer to reaching that goal, though, and he'll have the franchise's support when it finally happens.

"We're rooting for him," Russ said. "We are his biggest fans; I want to see him get back out there and play football. I know that's what he loves to do. And that's what he's worked very, very hard to do."