SANTA CLARA, Calif. -- It's a Tuesday afternoon, better known in the San Francisco 49ers locker room as the day off, and defensive end Nick Bosa is sitting at home patiently waiting as he fires up his Xbox.
Earlier in the day, Bosa and linebacker Fred Warner agreed to hop online and unwind via some video games. So Bosa waits. And waits. And waits some more.
"[He's] just really passionate," Bosa said. "He's the last guy in the facility every day. He didn't leave [the 49ers training facility] until like 5 [p.m.], and it was our off day. That just shows what kind of player he is and what he wants to be."
Platitudes about players being the first to arrive and the last to leave are cliché in NFL locker rooms, but in Warner's case, they're true. Bosa's story is one of many about Warner's relentless work habits. 49ers general manager John Lynch has previously recalled walking through the locker room at 9:30 p.m. during the offseason, only to find Warner sitting there staring at tape on his team-issued iPad. Defensive coordinator Robert Saleh regularly sees Warner sitting alone, eating breakfast with that same tablet fired up in front of him.
If the Niners' fearsome defensive front is the engine that drives the defense and the secondary represents the wheels that make it go, Warner is the on-board computer. Everything Saleh calls and the tweaks that follow go through him. Warner is a studious, sideline-to-sideline performer who doesn't get enough credit for San Francisco's defensive renaissance.
Warner led the Niners in tackles (123) while playing all 16 games as a rookie. He has been even better this season, racking up a team-leading 92 tackles and adding more splash plays, such as three sacks and three forced fumbles after having no sacks and one forced fumble in 2018. Through 12 games, Warner is the only linebacker with at least 90 tackles, three sacks, three forced fumbles and six passes defended.
The type of player Warner wants to and could be? The sky is the limit, according to teammates and coaches.
"He's the quarterback, and it all starts with him, and he does a phenomenal job," Saleh said. "Major improvement from a year ago, but it started last year."
When the Niners used the 2018 No. 70 overall pick on Warner, they had a pretty good idea that he would step into the role of middle linebacker, which is, as Saleh noted, the defensive signal-caller. After all, Warner scored a 32 on the Wonderlic, and Lynch joked after drafting him that Warner could "moonlight at Google."
It's little wonder that the Niners didn't wait long to give Warner the "green dot," making him the designated player who has a radio receiver in his helmet to communicate with the coaching staff on the sideline. With that green dot comes serious responsibility, and it's a job that has only grown in Warner's second NFL season.
Before each snap, Warner gets the playcall, relays it to his teammates in the huddle, sets the defensive front, looks at the offensive formation, searches for indicators that might tip off a run or pass, and then adjusts the alignments accordingly.
Warner handled all of that so well in his first season that Saleh has entrusted him with more freedom to make checks and tweak alignments -- especially on the back end -- in his second season, during which, Warner notes, the game has slowed down for him quite a bit.
"I like being able to play fast and anticipate what the offense is giving me and not having to worry about making a million checks, too," Warner said. "When you find out what those indicators are pre-snap, you can kind of anticipate what they're about to run instead of trying to react late and all that kind of stuff."
While Warner's growth on the mental side has been no surprise, it has overshadowed what he has brought to the table physically. At BYU, Warner, who is listed at 6-foot-3, 230 pounds, played a hybrid safety-linebacker position the Cougars referred to as "the Flash." It left some wondering if he would be big or physical enough to handle playing stack linebacker in the NFL. That has been answered emphatically.
Beyond his production, Warner has come into his own as a defensive leader. The offseason addition of outgoing linebacker Kwon Alexander has helped Warner unleash a swagger heretofore unseen. During training camp, he began a tradition of starting every practice by breaking out of stretching, screaming at the top of his lungs and sprinting to the middle of the field to lead the pre-practice huddle.
With Alexander out for the season because of a torn pectoral, Warner has grown even more vocal, finding the right mix between defensive nerve center and outlandish hype man.
"It does take some balance," Warner said. "That’s why it was good when Kwon was out there because I let him handle a lot and most of that. I would still bring it, but at the same time, I've got to remember that I have to run back to the huddle and remember I'm screaming the call at all 10 players, so it depends on how my air is."
A breakthrough performance in Week 10 against the Seattle Seahawks on Monday Night Football opened some eyes, as Warner finished with 10 tackles, two sacks, a forced fumble that led to a touchdown and a pass breakup. Although credit for leading the Niners' top-ranked defense has been slow to come from the outside, his teammates don't hesitate to offer praise.
"He works hard, he plays hard, he plays at a high level," cornerback Richard Sherman said. "At the end of the day, you get respect for that. You get respect for how you play on Sundays, Mondays and Thursdays ... He makes everything happen. That is a testament to his hard work and dedication. I think the entire defense respects him and respects what he’s able to do."
Even if Warner is too busy studying to notice.