Kurtenbach: The 49ers had their first look at this season’s toughest opponent (and no, it wasn’t the Rams)

On Sunday, the 49ers finally reckoned with a force that could stop them from winning the Super Bowl this season.

And no, it wasn’t their Week 2 opponent, the Rams.

It was injuries.

After escaping from Week 1 with enviable health, the harsh reality of the NFL showed up in Week 2.

The 49ers’ top-line talent stands out from the rest of the league this season. And that top-line talent stands out from the rest of the 49ers roster.

Yes, the drop-off is always significant between star player and reserve, but the 49ers have, in the past, built deep rosters under general manager John Lynch and head coach Kyle Shanahan. It’s a strategy that has paid off.

That is not how this 2023 team was built, though.

No, on this squad, the difference between star and backup is precipitous this season at several positions.

It’s enough to torpedo a season.

And the position where the difference between the best and the rest is largest might be wide receiver.

That’s what made Brandon Aiyuk injuring his shoulder on the first series of the game and Deebo Samuel going to the sidelines with what appeared to be a back injury in the second half so scary for San Francisco on Sunday. Both players are irreplaceable.

And while both were able to return to the game, with Samuel brushing off his injury scare, Aiyuk spent a solid portion of the game on the sidelines and was targeted only once in the second half.

While Shanahan said, “I think he’ll be alright” for Thursday’s game against the Giants, that might have been wishful thinking heading into a short week.

That’s because it’d be generous to say that Aiyuk’s in-and-out replacement, rookie Ronnie Bell, affected the game in a positive way as a receiver Sunday.

To go from a player like Aiyuk — the NFL’s offensive player of Week 1 — to Bell, a solid prospect but not-ready-for-prime-time player, would seriously hamper the Niners’ offense going into Thursday’s prime-time game.

And it’d be a joke to imagine someone else filling the Samuel role in this offense.

At wide receiver, tight end, and left tackle, the 49ers must pray for health. This team has no reasonable replacements, facsimiles, or plug-and-play options behind Aiyuk, Samuel, George Kittle, or Trent Williams.

Saying “next man up” is just a coping mechanism — the absence of any one of those offensive players could bring about a loss for the Niners.

(Christian McCaffrey might be the offense’s best player, but he has a very capable if less dynamic, backup in Elijah Mitchell.)

Ironically, while most teams would cancel their Super Bowl aspirations if their quarterback were injured, the Niners might be best insulated at that position (just like last season) with Sam Darnold and Brandon Allen backing up Brock Purdy.

On defense, where injuries seem even more common, the same irreplaceability follows both starting linebackers, Fred Warner and Dre Greenlaw. The 49ers’ linebacker once enviable linebacker depth is now paper-thin — losing either Warner or Greenlaw would dramatically change the Niners’ defense. The absence of Nick Bosa would also be huge (even if he’s struggled so far this season). I’d also put free agent signing Javon Hargrave in that irreplaceable camp — he’s unlocked the best from his spot at defensive tackle.

The Niners’ lack of a deep bench is no bug — it’s a feature of both the Niners’ roster-building tactics (retain elite players by paying them elite money) in the salary cap era.

It’s also a byproduct of trading missing on draft picks and trading away three first-round draft selections to pick Trey Lance. The Niners also traded second-, third-, and fourth-round picks in the 2023 draft to acquire McCaffrey.

The Niners would at least make one of those trades again. I’ll let you guess which one it is.

And while the Niners carry plenty of salary cap room for this season, the truth remains that they are built to ride their best players to the Super Bowl.

But the Super Bowl isn’t until February, and football is a full-contact game.

So it’s not the Rams, Cowboys, or Eagles the Niners need to fear this season.

It’s the injury bug. It will define the Niners’ 2023 for better or for worse.