Armstead, a first-round draft pick like Kinlaw, also struggled to stay on the field early in his NFL career. He turned in full seasons from 2018 through 2021, though, and has become a well-respected member of the 49ers' stout defensive front.
Kinlaw is making his presence felt during training camp, and Armstead believes the defensive lineman is poised for a big season.
"JK has been balling," Armstead told reporters after Monday's practice. "It's been great to see his progress and his process. I dealt with injuries early in my career and really couldn't find my footing. Once I was able to string along some good health, I was able to play some good football. And he's been looking amazing. He's healthy, and he's been dominating."
The 49ers opted not to exercise Kinlaw's fifth-year option. That means the defensive tackle is entering the final year of his rookie contract. He may need a big season to remain with the team that made him the No. 14 overall pick in 2020.
That will also require staying healthy.
"Kinlaw has been unbelievable," head coach Kyle Shanahan said last week. "I mean, you guys see how he looks, and he's gone a full year with no setbacks. And so to get through OTAs with that and then our 40 days away, it continued. And as that happens, he just keeps looking better and better."
Kinlaw underwent reconstructive knee surgery in 2021. A setback this last season forced him to miss 11 games. For Armstead, the whole situation feels a little too familiar.
"I've been through a lot in this league, going into my ninth year," Armstead said. "[I've] been in a lot of situations, and I know what it's like to deal with some injuries, and deal with the pressure, and what people may say, and trying to fight to get back.
"And I've also dealt with the other side of having some success on the other side of that too. So it's been great to see [his success in practice], and he's going to have a big year. ... I don't think people understand the mental toll injuries really take on you; waking up with pain and those type of things. That can lead to depression and a real bad mental state.
"So I'm sure feeling healthy and feeling more like himself is making him happy, and he's able to use his abilities, his God-given abilities, and the ones he's been training and working on, to go out there and do something you love. So it's great to see him happy and playing well."
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