SANTA CLARA, Calif. -- This is the Brock Purdy era, his teammates tell us. And it's a good thing, because once again the San Francisco 49ers' toughest opponent will be their own injured list.
The number of players on it would have grown to 16 on Friday after news arrived that defensive end Nick Bosa strained a calf doing high knees before Thursday's practice. He is out for Sunday's game against the Arizona Cardinals and will miss "a few weeks," coach Kyle Shanahan said Friday. That normally would mean Bosa would go on the injured reserve list for four weeks …
… but there is no vacancy at the ER -- sorry, the IR. The 49ers are running out of spots, and general manager John Lynch will have to make like Dr. Robby to juggle which eight players -- that's the limit -- he and Shanahan want to activate during the regular season.
While receiver Ricky Pearsall, tight end Jake Tonges and defensive tackle Alfred Collins are out for the season, the Niners expect to bring back receivers De'Zhaun Stribling and Christian Kirk, as well as offensive lineman Austen Pleasants and defensive tackle C.J. West.
Rookie defensive end Romello Height, who had hand surgery, is not on the list but is also out Sunday, as is rookie defensive tackle James Thompson Jr.
Shanahan was asked after practice if it feels like Groundhog Day.
"Losing Bosa was rough yesterday, he said. "Losing six out of the 10 D-linemen in the last two weeks that had made our team is a little unusual. I don't think I've been a part of that, so that has been different."
The 49ers were already thinking about not putting receiver Demarcus Robinson (ankle) on the injured reserve list, but now they may have to, rather than carry his and Bosa's dead roster spots for three to four weeks.
(Defensive end Mykel Williams, coming off knee surgery, was designated physically unable to perform before training camp, so he is on a different list. He is expected to start practicing again next week.)
If the 49ers were at one point curious what second-year linebacker Nick Martin or veteran cornerback Nate Hobbs could bring to the mix after they healed, that might now be tabled until next season. The 49ers are well ahead of last year's ridiculous injury pace -- the neighboring substation ghosts are chuckling, while the trainers may be facing some uneasy questions -- so luxury moves are out with 15 games still left.
And … what will the 49ers' defense look like without Bosa against the Cardinals, Denver Broncos and Seattle Seahawks over the next three weeks? We heard from a couple of general managers at the spring owners' meetings that while linebacker Fred Warner is indeed special, it's Bosa who makes the 49ers' defense go with his pass rush and run defense.
Now, the 49ers will likely have to start Khalid Kareem, 28, opposite Keion White on the edges with Bosa and Height out. It will be the second career start for Kareem, who took a last-minute flight to Australia for the 49ers' opener after being signed three weeks ago. Rookie Gracen Halton will start inside next to Osa Odighizuwa, with Naquan Jones, signed off the Minnesota Vikings' practice squad Wednesday, backing them up.
Purdy keeps getting better and more confident, according to Lynch, despite losing four of his top five receivers entering training camp. He's completed 80 percent of his passes and thrown five touchdown passes to help the 49ers start 2-0. They're averaging 31 points a game, and Purdy and company put up 41 points the last time he faced the Cardinals.
"He looked like he was just at practice out there, wheeling and dealing," left tackle Trent Williams said after Sunday's win over the Miami Dolphins. "We're starting to witness Brock's prime, and I think it's going to be a sight to behold."
The Cardinals' defense is built on disguises, with fourth-year coordinator Nick Rallis often using three safeties and post-snap rotations to confuse offenses. That works better against teams who don't face them twice a season.
The 49ers, meanwhile, have a lot of the same pieces, but their offense is always evolving. For example, they're using even more pre-snap motion, or lining up in shotgun only a league-low 39 percent of the time (down from 53 percent last season).
"If you look at the Niners' offense compared to two years ago," tight end George Kittle said, "it's completely different. Besides our basic lineup and running outside zone, everything's so different now. All of our motions and gaps and how we structure plays and play action, everything is so different.
"Kyle's offense has grown and changed so much."
So has Purdy, who is living up to his preseason pledge to make more plays with his feet. He ran for 30 yards and a touchdown Sunday, and the play of the day was a rollout to his left on which he pumped-faked across his body before dropping a perfect 27-yard pass to Mike Evans in a tight window.
"Brock has that special ability to play within the scheme and then know when to play football like you do when you're a kid," running back Christian McCaffrey said. "There's a good balance of doing your job and being extremely detailed on what's asked of you, but the play might not be there, and you gotta go make a play.
"Brock's always looking for that and seems to always find it. … That's what makes him elite."
It also helps his teammates relax when Purdy never seems to get nervous or stressed.
"He's always that guy you can look to in the middle of a game and get that calmness from, no matter how the game is going," Williams said. "He's got so much composure and focus.
"I respect that about him the most. I know his job comes with the most pressure."
Especially when he keeps having to learn new teammates' names.
This article originally appeared in [The Athletic](https://www.nytimes.com/athletic/7631132/2026/09/26/can-49ers-brock-purdy-prevail-over-teams-toughest-opponent-the-injured-list/).