SANTA CLARA, Calif. -- For the big defensive tackle wearing No. 99, it's the number at the opposite end of the spectrum that matters most: 0.

That's how many practices, walkthroughs and games Javon Kinlaw has missed for the San Francisco 49ers this preseason. To this point, Kinlaw's career has been plagued by persistent right knee issues that have prevented him from delivering anything near the expectations that came with being the No. 14 overall pick in the 2020 NFL draft. Those injuries have limited Kinlaw to only 24 games and 817 snaps in three seasons.

Now, Kinlaw is participating without restriction and healthy for the first time since becoming a Niner.

"Playing with one-and-a-half legs is no good," Kinlaw said. "You think about it every snap versus [having] two good legs. My body is improving as a whole [and] I've been able to do some things I've never been able to do. So it gives me superior confidence."

Confidence has been hard to come by for Kinlaw since he arrived in San Francisco. Despite concerns over potential arthritis in his knee as far back as the 2020 pre-draft process, the Niners traded star defensive tackle DeForest Buckner to the Indianapolis Colts for the pick they eventually used on Kinlaw. The hope was that Kinlaw could eventually approach what Buckner offered to the 49ers' defensive line.

Kinlaw played 14 games as a rookie but suffered a torn ACL in 2021 and battled recurrent issues with fluid in the knee in 2022, which limited him to a combined 10 games over the past two seasons. For his career, Kinlaw has 45 tackles, 1.5 sacks, an interception and a 3.4% pressure rate. The relentless injury problems have prevented Kinlaw from getting the playing time necessary to smooth out the edges in his game, most notably his propensity for playing too high.

All that resulted in the Niners deciding not to pick up the fifth-year option on Kinlaw's rookie contract in May. He will play this season at a cap number of $4.93 million and then be eligible for unrestricted free agency. In the simplest terms possible, Kinlaw's NFL future rides on whether he can finally at least tap into some of the potential the Niners saw when they drafted him out of South Carolina.

"We know how talented he is, and every year we're hoping he can come back and have the health and play the way that we know he's capable," 49ers coach Kyle Shanahan said. "And every year it's just heartbreaking with how hard he's worked and what happens with him. And this year it's been so encouraging because it's the first year that he's gone from February all the way up to now with no setbacks ...

"You know how much it means to him, you know how much he's put into it ... probably as much as I've seen any player. And it's hard when you have those three years where you don't have good luck ... You're really pulling for the kid."

In a short career full of fits and starts, Kinlaw has previously offered hope of a breakthrough. Early last season, Kinlaw enthusiastically declared that he was back to full speed before the knee issues returned and cost him 11 regular season games. The previous unrealized potential is enough to wonder: What will make this time any different?

To answer that, Kinlaw points to an offseason in which he spent nearly every day at the Niners training facility working out. Defensive line coach Kris Kocurek recalls seeing Kinlaw in the facility as far back as February and noted that Kinlaw hasn't missed a day or rep the entire offseason. When Kinlaw wasn't at the facility, he popped into regular pilates classes.

While Kinlaw arrived in good shape, the bigger offseason focus was on body mechanics. Between pilates and his regular workouts, Kinlaw aimed to improve mobility and stability, building up smaller muscles that would allow him to come off the ball quicker, play lower and get underneath blockers.

"Just not being able to play as low as I needed to, that's why I went to the lab and I really focused on my body mechanics," Kinlaw said. "When the pad level come down, I don't believe nobody could stop me."

Also not hurting Kinlaw's bounce back efforts is reduced pressure to play a starring role. The 49ers signed star defensive tackle Javon Hargrave to a four-year, $84 million contract in March, ostensibly admitting that the Kinlaw pick hasn't worked out as hoped. That means Kinlaw won't be asked to play 50 to 60 snaps a game. Rather, he can serve as a primary backup to Hargrave and fellow defensive tackle Arik Armstead and go full speed for 25 to 35 snaps per game.

As the team's longest-tenured veteran, Armstead has stayed by Kinlaw's side, reminding him there are good things on the other side of the disappointment that accompanies injuries.

"It's been great to see his progress and his process," Armstead said. "I dealt with injuries early in my career and really couldn’t find my footing, and once I was able to string along some good health, I was able to play some good football. He's been looking amazing. He's healthy and he's been dominating."

During training camp, Kinlaw has impressed teammates and coaches. Defensive coordinator Steve Wilks has been wowed by Kinlaw's speed and willingness to chase plays down field. In one-on-one pass rush and team drills, Kinlaw has flashed a deeper move set that goes beyond the simple bull rushes he's favored his first three seasons. He's even lined up at end occasionally, a possible new wrinkle for Wilks to deploy.

The Kinlaw reclamation project has been an encouraging summer storyline but all parties know the biggest task -- translating a promising offseason into on-field production -- still remains.

"[The] arrow is pointing up," Kocurek said. "[It's] one of the more gratifying things since I've been here, to see the amount of work that he's done and to see it start to come to fruition ... It's just gotta continuously get a little bit better."