Kurtenbach: Here are the struggling 49ers’ four biggest problems (and how to fix them)

We’re not going to talk about vibes, energy, or spirits.

We’re not going to call out curses, snakebites, or luck.

No, we’re going to talk about some X’s and O’s here because, clearly, something is wrong with this 49ers team that cannot be solely an issue of culture or temperament.

These are the four biggest problems facing the 49ers on the field right now, and my thoughts on how this team can correct them — before it’s too late:

They have no last line of defense

» The 49ers have four safeties on their active roster.

Not one of them is a free safety.

That, friends, is a big problem for a team that ostensibly wanted to play more single-high safety looks.

You need not just a free safety to do that, but a good one.

And yet, Ji’Ayir Brown has proven incapable of holding down that role full-time — he was attacked relentlessly the first three weeks of the season — and the triumvirate of George Odum (benched), Talanoa Hufanga (injured, benched), and Malik Mustapha (rookie) should all be considered box strong safeties. (Perhaps Mustapha has more, but that’s a big ask at this point in his career.)

If my belief that safeties are destiny is, in fact, correct, I don’t like the outlook for the 49ers. We often talk about the best quarterback in any game typically winning the game. Well, the Niners have been beaten on the back end of the defense the last four weeks — they’re 1-3 in those games.

How can the Niners fix this? A trade for a proper free safety would be good, but given the market, the Niners’ current roster state and the need to hold onto draft picks (it’s their only source of cheap labor moving forward) that’s a big ask.

So tactically, moving to a two-high safety system might prove advantageous, allowing the young safeties to keep the game in front of them and fire downhill against the run. That’s not a fix-all, but it could mitigate the damage given current conditions.

It’s time to dump the idealism and become pragmatic.

They don’t score touchdowns in the red zone

» The Niners cannot score in the red zone. Is that an early-season blip — something that will correct naturally over time — or a symptom of a larger issue?

Can I say it’s a bit of both?

The Niners are not an incompetent offensive team, despite what some foaming-at-the-mouth folks might say. They’re second in the NFL in red-zone opportunities, and there is ample talent to score inside the opponent’s 20-yard line.

Yet here they are, kicking short field goals like they count double and scoring a touchdown on only half of their goal-to-goal series this season — 31st in the league and a far cry from the 83 percent touchdown clip they posted last season. (Shoutout to ESPN’s Nick Wagoner for first pulling those stats.)

So what’s the deal?

The absence of Christian McCaffrey looms large. He was a man-to-man cheat code on a team of zone-beating weapons — a necessity in tight-quarter combat.

Pair him with Deebo Samuel, and you have a cheat code to the test. Those are two players around whom defenses build their game plans. One player’s movement before the snap gives Purdy the necessary zone-or-man indicator, and the second player’s movement counters that defense.

So far, the Niners only have one, and without a legitimate pass-catching threat in the backfield (much less one that can be flexed out wide) and an offense that’s using far less stretch play-action because of increased shotgun formations, it takes away from the offense’s dynamism. It’s just guys versus guys in tight space, and that’s not Kyle Shanahan or the 49ers’ game.

So what can be done?

McCaffrey can heal and play. That would be huge.

But the Niners should also consider using Samuel in the backfield — a la 2021 — more often, particularly close to the end zone in the meantime. That can get the defense spinning a bit. How about a shovel pass? Just one.

Purdy said Sunday he needs to be more aggressive in the red zone when throwing the ball. That would help, to be sure.

And if McCaffrey isn’t coming back, finding a true pass-catching back — a third-down, scat-back type, a la Jet McKinnon — could do wonders. I don’t think Isaac Guerendo is the answer there but you can at least try it out in the meantime.

They can’t win against man coverage

» Samuel doesn’t separate in pressing man-to-man coverage. Never has, never will. Jauan Jennings can only do it if he lines up against off-man coverage, which he sees in the slot. George Kittle has to block snap after snap for the sake of the outside-zone run game.

On Sunday, the Niners ran a third down where both Ronnie Bell and Trent Taylor were on the field. I’m sure the Cardinals weren’t too concerned about being burned on that snap.

Of course, Brandon Aiyuk can win off the line of scrimmage, and he did, repeatedly, on Sunday, to the tune of 147 receiving yards, with nearly 100 in the first quarter, when Arizona was almost exclusively in man-to-man.

It highlights the bet the Cardinals made on Sunday. It’s the same one the Chiefs made in the Super Bowl — and the Rams and Patriots copied earlier this season:

If you play man-to-man against the 49ers, you can mess up the receivers’ timing in a timing-based offense because they don’t have natural separators. And yes, Aiyuk can get away from man-to-man coverage, but the gamble these teams have made is that No. 1, he’s not at full speed this season (Arizona found out the hard way Aiyuk, in fact, is back in form), and No. 2, that the Niners’ offensive line isn’t good enough to allow Purdy the time and windows to take advantage (this is how the Chiefs won).

So yes, the Niners might pick up 15-, 25-, 35-yard chunks with Aiyuk, but those will be the exceptions. Man-to-man schemes also allow teams to stack the box to sell out against the run — something that was obvious early Sunday.

Purdy saw all this coming. When asked this week about what he’s seeing from opposing teams.

“I do feel like there may be a theme of man coverage,” he said. “We’ve just got to beat the guy in front of us, and then, for me as a quarterback, I’ve got to be accurate with the ball, and we’ve got to execute.”

“That’s football at its finest… I feel like we may see that a little bit more, but at the same time, you never know.”

But now the Niners do know. Not every team will want to play man-to-man against San Francisco, but the principles will be the same: If you force the Niners into a boom-or-bust offense, they will often go bust.

So, how does San Francisco fix this?

It feels ridiculous to pressure rookie wide receiver Ricky Pearsall, but he looks like someone who can separate at the NFL level. His inclusion in the lineup would give the Niners two such receivers and perhaps change the paradigm for defenses.

Otherwise, Purdy will have to continue channeling his inner Russell Wilson and extending plays with his feet, giving receivers more time to find some separation and himself more time to find them.

They can’t stop the run

» Outside of a trade for a two-gap-stuffing defensive tackle, the Niners have to ride with what they have on the defensive line.

But it seems prudent to trade out linebacker De’Vondre Campbell for Dee Winters. The latter might not know what he’s doing out there, but he makes up for it with aggression and speed. The opposite is true of Campbell, whose lost steps are repeatedly attacked by opposing offensive coordinators. It doesn’t matter if you know what to do if you can’t do it.

With only one practice before Thursday’s game in Seattle, I don’t think you can make the move right now, but the mini-bye going into the Kansas City game is the perfect time to make the swap.