A little more than a week ago, Kyle Shanahan joked that he finally got through a press conference without reading off an injury list. That streak didn’t last. The injury bug circled back around, and this time it landed on linebacker Tatum Bethune, who’s now expected to miss multiple games. That puts Curtis Robinson squarely in the spotlight.

“Curtis Robinson will be the first-team middle linebacker with Tatum Bethune injured,” journalist Nicholas McGee wrote on X.

Shanahan confirmed Bethune’s setback on Thursday and named the five-year veteran as the 49ers’ new starting MIKE linebacker. Robinson has mostly made his living on special teams, but this year he’s quietly played more defensive snaps than at any point in his career. Now the workload is going to shift into a full-time job.

So far this season, he’s logged 88 snaps on defense (just over 12 percent) and nearly 64 percent of the special teams reps. That defensive number is about to climb fast.

When Bethune went down on Sunday, Robinson slid in and finished the game. Shanahan sounded comfortable with the idea of him staying there.

“It’s been good that Curtis has been here. Always been practicing for this moment, but it’a just like when you’re missing a quarterback or a center. It’s not just the ability of the guy, but everything runs through that position. The MIKE by far on the defense, getting everyone lined up, getting the adjustments with all the motions,” Shanahan said.

“It’s a huge deal, schematically, mentally, the challenge of it, but Curtis is the right dude for that.”

The move does raise a natural question: why not rookie Nick Martin? Some fans wondered if this was a comment on Martin’s progress, but Shanahan’s approach makes sense. Robinson has some playcalling experience, and tossing a young linebacker into the deep end before he’s ready in an already injury-marred season might be a risky affair.

And we may see Martin suit up soon, because it looks like Bethune is going to be out for a while.

Tatum Bethune to miss multiple weeks

Fred Warner still isn’t back, and now the 49ers are staring at another hole in the middle of their defense. This time it’s Tatum Bethune, who’s dealing with a high ankle sprain and is expected to miss some time.

Bethune isn’t Warner, of course. But he’s been steady and dependable, a sure tackler who piled up 60 stops in just five games before going down in the team’s 41-22 win over the Arizona Cardinals. In a season where San Francisco has watched its defensive depth thin out week by week, he was one of the few constants. The hope is that he can make it back before the year is over and bring a little more stability.

For now, though, it leaves the 49ers stretching the linebacker depth chart as far as it’ll go. Curtis Robinson steps into the lead role. Behind him are Dee Winters, Luke Gifford, and Nick Martin, the rookie who spent most of the fall as a weekly inactive player before finally earning a spot on the gameday roster. They’re running out of reasonable options, and it’s only November. However, there is at least one silver lining.

After the Panthers and Browns matchups, the 49ers finally get their bye. There’s no firm timeline for Bethune, but with that break built in, there’s a path for him to be back on the field for the Titans game. The question is whether those games before the bye will still mean something.

If San Francisco can’t navigate these next two weeks, the climb back into the playoff picture looks bleak for Kyle Shanahan’s team.