Dieter Kurtenbach: The 49ers keep losing stars. But Kyle Shanahan, Brock Purdy won't let them lose games.

SANTA CLARA, Calif. — It never stops.

Football is a game with a 100% injury rate, a true contest of attrition.

But no one does attrition quite like the San Francisco 49ers. The injuries continue to pile up — in all the wrong places, mind you — at a near-comical rate.

And yet so do the wins.

That’s what happens when you have a great head coach and a quarterback playing as well as, or better than, anyone else in the game right now.

The situation for the 49ers on Sunday can be presented in many ways.

The first is that Brock Purdy had four touchdowns and 331 yards from scrimmage with no turnovers, George Kittle and Christian McCaffrey looked like the 2023 versions of themselves, combining for three scores, and the 49ers beat the feisty Arizona Cardinals 36-30 to move to 3-0 on the campaign.

But if you watched this game, you know it’s so much more complicated than that.

Yes, those things happened, but they happened amid a constant string of injuries that turned the 49ers sideline into an episode of The Pitt.

Mike Evans left with a rib injury.

Trent Williams left with a stinger. Neither returned.

Both starting cornerbacks left the game to be evaluated for concussions. They did return.

Dre Greenlaw hurt his quad. His replacement picked up a stinger. (What is a stinger, anyway?)

There were several points in the game where there was a line to get into the blue injury tent. I wish I was kidding.

After all, this is a team that came into the game down six of the 10 defensive linemen they had at the start of the season (which was this month) and then lost another to game-ending cramps Sunday.

Or perhaps this absurd attrition is best explained by wide receiver Jordan Watkins’ wild week.

Inactive for the first two games, the second-year receiver entered practice on Wednesday with an opportunity to win game snaps after DeMarcus Robinson’s ankle injury in Week 2, but the 49ers weren’t sure they wanted to play him. By the end of the week, he was trusted to play, but as the last option. By the end of Sunday’s game, he was the Niners’ top receiver. (He had two nice first-half catches.)

Injuries are a harsh reality of the NFL, but this is not the reality 31 other teams face every week.

But at this point, it’s standard operating procedure for the 49ers, where nothing is normal.

After all, this is a team that saw Deebo Samuel — who is looking like a prime version of himself in a more limited role — finish the game with 80 yards receiving and no catches. Yes, you read that right: zero catches.

(It’s a quirk of official scoring on the 82-yard hook-and-lateral play that scored the Niners’ first touchdown Sunday.)

It’s natural for those of us in the press box, the fans in the stands, and everyone watching at home — the folks with a bit of time to think — to question how the Niners keep going when players — top players, at that — keep dropping.

And the answer is exactly what the NFL wants: the head coach and quarterback find a way.

Head coach Kyle Shanahan can’t think about anything other than the next play when Evans or Williams leaves the contest. There’s no window to say “woe is me.” The game doesn’t stop. You just have to adjust.

“You don’t have time to think about anything else,” Shanahan said.

And Purdy could ruminate over the strange monkey’s paw his career has been. He was never supposed to be the 49ers’ starting quarterback, much less a franchise-level player and, as of Week 3, the MVP frontrunner. Perhaps the cosmic counterbalance has been that things need to be as difficult as possible, year in, year out. (Add in a Super Bowl overtime loss in the year where things did, in fact, go right.)

“Obviously when I see my guys go down, it sucks,” Purdy said. “As I’ve grown, all I can do is control what I can control … and leave it at that.”

And boy, is Purdy in control.

That level of swagger, paired with Shanahan’s play calling has the Niners’ offensive engine humming, even with spare parts picked up at the swap meet.

“I think Kyle is the best in the league in terms of calling plays, his system … calling the right plays at the right time,” Purdy said. “That’s the difference between a good play caller and a great play caller.

“Any time a play call comes in, we’re confident that we have the best in the league at doing this.”

Even if you’re introducing yourself to a couple of guys in the huddle.

And as for having Purdy out there as his on-field avatar, Shanahan feels that comfort, too.

He doesn’t have to hold back a thing in the playbook. His full depth of knowledge can manifest on the field. Shanahan said it’s the third time he’s had a quarterback like that in his play-calling career, which now spans 19 years.

He had it first with Texans quarterback Matt Schaub, who, when Shanahan was 29 and in his second year as a play caller, led the NFL in passing yards.

The next time he had it was when Matt Ryan won NFL MVP for the Falcons in 2016 with Shanahan as his offensive coordinator.

And the third time, with Purdy. “[F]or four years,” Shanahan added.

Purdy was only seventh in the NFL in passing yards after Sunday’s game, but at 3-0 and with nine passing touchdowns to one interception and zero sacks taken — not to mention the constant game of musical chairs being played around him — he should be considered a serious contender to follow in Ryan’s footsteps.

The Niners won’t have much of a choice but to lean on that the rest of the way.

Perhaps the NFL’s marketing is correct. Perhaps this game is as simple as coach vs. coach, quarterback vs. quarterback, week in, week out. Laypeople who try to find small mismatches and tactical quirks on the tape are fools.

If that is, indeed, the case, then the Niners are sitting pretty.

Even if seemingly half their team is sitting in the training room.

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