SANTA CLARA, Calif. -- After playing just 11 snaps in his first NFL game on Sept. 10, San Francisco 49ers rookie linebacker Reuben Foster departed with a high ankle sprain. The injury didn't allow him to return until Oct. 22. Absent the ability to practice, Foster found ways to stay involved, including film study.

One problem: He had just those 11 snaps to watch. So he did. On a loop.

"I watched that game repeatedly, over and over and over and over and over again," Foster said, laughing. "Just to say, ‘Do I still got it?’ I got hurt the first game. It was hard."

Finally healthy and able to make it through his first two complete regular-season games the past two weeks, Foster now has plenty of film to watch, and the Niners look to have a player who can be a focal point of their defense and a cornerstone of the franchise for years to come.

For anyone watching that film, it's hard not to see Foster constantly around the ball, making tackles from sideline to sideline, much as the Niners envisioned when they traded up to the end of the first round to draft him in April. In the past two games, Foster has played 135 snaps, coming off the field only briefly after aggravating his ankle injury.

Given the chance to play four quarters, Foster has posted 24 tackles in those contests, and Pro Football Focus had him down for four run stops and just two receptions allowed in coverage last week against the Giants. PFF also graded him as the Niners' best player and the fourth-best linebacker in the league in Week 10.

Foster's performance hasn't gone unnoticed by teammates.

“It’s like having 12 people on the field," defensive lineman Ronald Blair III said. "He’s all over the place. He’s really smart on the field, too. He’s a great tackler. I’m honored to have him back there. He’s a great player.”

With Foster already garnering lofty praise, it's worth considering just how much upside he still has. Foster is largely able to get by on instincts and athleticism right now, but he's doing it while trying to settle into a position. The Niners intended to have Foster play weakside linebacker after Malcolm Smith's season-ending injury before eventually handling middle linebacker duties. But when they released NaVorro Bowman last month, it expedited Foster's move, at least temporarily.

Since Foster was unable to get much work in the middle before Bowman departed, the 49ers quickly decided that changing his role might have been too much too soon and prevented him from making the type of impact they were looking for. So they shifted course, moving Foster back to the weakside with Brock Coyle in the middle in the base defense.

That not only allowed Foster to play the position he had played most since his arrival but also gave Coyle the extra responsibility of handling the playcalls and wearing the green dot indicating he has radio communication with the sideline in his helmet. When Coyle isn't in the game, the Niners use signals from the sideline to make the calls.

“Not to say Reuben can’t do it, because he does a great job with it," defensive coordinator Robert Saleh said. "But having [Coyle] and Reuben on the field at the same time being able to talk to the people around them, and also allowing Reuben to focus on just being a football player, was the main deciding factor.”

In other words, the next step in Foster's evolution will be getting to the point where he can not only cut loose and continue making plays all over the field, but to have such an understanding of the defense that he can do that while communicating play calls and ensuring his teammates are lined up properly. Saleh insists Foster could already do that, but because he got such a late start on playing in the middle, the 49ers didn't want to potentially hold him back by putting too much on his plate.

The plan remains for Foster to eventually follow in the footsteps of franchise luminaries Bowman and Patrick Willis and become the centerpiece of the Niners defense.

"I do think he’s a natural Mike [middle linebacker]," coach Kyle Shanahan said. "He has the natural charisma and command of the huddle of the defense. You know, missing a lot of time this year and getting thrown in there, I think it makes it easier for him to play fast, not having to worry about all the communication and help everyone get lined up and make the calls and stuff. So, I think right now, it helps him play the most freely at [the] Will [weakside linebacker] position. I think we'll evaluate that in the offseason and see where he's best. The more work he gets, I know Mike will become second nature to him. We'll see how it is with our roster next year with all the other linebackers, and we’ll do what's best for our team, which I think will also be best for Reuben. He gives you options.”

Foster has said he will do whatever is asked of him. If that means playing defensive end, it's a job he will embrace. But he also acknowledged that he wants that little green dot on the back of his helmet, for it can also be viewed as a precursor to having the captain's "C" on his jersey some day.

"I know what their goals are, and that’s the green dot," Foster said. "At the end of the day, I’m working towards it. I’m not going, I’m going to try not to let anything hold me back. I’m not going to let anything hold me back, because I want that green dot as well."