In order to win the Super Bowl, the Rams need to draught or sign a running back.

By the time San Francisco’s Christian McCaffrey had darted and dashed and danced, the demoralized Rams were perhaps left with one thought.

How could we let him get away?

By the time their own backs had stumbled and staggered and stalled, the beaten Rams were absolutely left with one mission.

Find a running game or lose a season.

So it went at Sofi Stadium on a Sunday afternoon filled with red jerseys and real angst as the San Francisco 49ers exposed the Rams for what they are, and what they aren’t.

They’re a defending champion with a super-sized hole at running back.

They aren’t making the playoffs unless they fill it.

Bolstered by a dynamic running game led by recently acquired McCaffrey, backed by another howling San Francisco home crowd, the 49ers beat the toothless Rams for an eighth consecutive regular-season game in a 31-14 decision that pointed the similar rivals in different directions.

The 49ers are 4-4 and surging.

The Rams are 3-4 and on the brink.

The explanation is not as simple as the 49ers outbidding the Rams for McCaffrey in a trade with the Carolina Panthers a couple of weeks ago, but it sure feels like it.

The fix is not as easy as the Rams acquiring a veteran running back by Tuesday’s trade deadline, but it sure looks like it.

In a game in which the Rams blew a 14-10 halftime lead by failing to sustain any offense or momentum in a scoreless second half, the difference was all in the feet.

The 49ers could run, and eventually soared. The Rams couldn’t run, and eventually sank.

The Rams were ultimately so demoralized by the difference in passion and physicality that they gained but 16 yards in their last four possessions in what some thought was an all-out surrender.

“I was kind of surprised when they gave up a little early,” 49ers defensive end Nick Bosa said in a pointed rip of the defending champs. “I think there was six or seven minutes left and they ran the ball on third down. I was hoping for some more pass rushes there, but I guess they didn’t have confidence in coming back.”

If the Rams could have run the ball, they could have stayed on the field long enough to stay in the game longer. They couldn’t. They didn’t. They know it.

“Point blank period, we have to do a better job of running the ball, there’s no getting around that,” the Rams’ Cooper Kupp said.

As if things weren’t bad enough, the game ended with Kupp unable to run after his ankle was twisted in a vicious collision. He limped off the field under his own power and said later he thought he dodged an injury bullet, but, seriously, why was coach Sean McVay even playing him during garbage time?

“That’s why you wanted to try to be smart getting out of the game,” McVay admitted. “I’m kicking myself for not running the football again, but I’m hopeful that he’s OK.”

Any potential injury could be double trouble. If the Rams lose Kupp, they will not only lose their best receiver, but also essentially their best running back.

“It’s huge, it is,” Kupp said of the running game. “It’s an obvious point of emphasis. You never want to be one dimensional.”

There is truly no dimension to the Rams’ 31st-ranked running attack. It’s virtually invisible, and Sunday it caused the offense to eventually disappear.

The 49ers rushed for 111 yards while the Rams rushed for 56 but the difference was bigger than that, just check out who was carrying the ball.

McCaffrey rushed for 94 yards and a touchdown, caught eight passes for 55 yards and a touchdown, and threw for a touchdown. The Rams’ leading back? It was practice-squad regular Ronnie Rivers, who rushed for 21 yards and caught four passes for 15 yards.

This is precisely what the 49ers had in mind when they acquired McCaffrey. This is also what the Rams had in mind when they sparred with the 49ers over his services.

The Rams obviously realized they needed McCaffrey, and they pursued him, but they apparently decided they couldn’t match the price of four draft picks, all in the first five rounds.

It’s hard to blame them. They already had spent great draft capital and money building last year’s championship team, and McCaffrey has a history of injuries, and it might not have been the best long-term fit.

But with Cam Akers in the doghouse, Darrell Henderson Jr. and Malcolm Brown not consistent enough and fifth-round draft Kyren Williams still nursing an ankle injury, surely they can make a trade for somebody who would be a fit, right?

I asked McVay if they needed to acquire a running back.

“No,” he said.

No?

“That’s not the problem,” he said, pointing to the team’s makeshift offensive line. “Whether it’s a running back or whatever it is, you still have to be able to get a hat on a hat and handle the movement up front no matter who’s running the football. The reason we didn’t run the football efficiently isn’t because of our backs.”

However, he added, “We are always looking for ways to upgrade the football team. We have a lot of things we need to address.”

Not to contradict McVay’s original answer, but here’s guessing they’ll spend the next 48 hours looking for a running back. The need was obvious Sunday from the moment they scored their first touchdown at the end of the first quarter.

It took them six plays to score from the two-yard line, and when they finally did, it was on a Matthew Stafford mad scramble during which he was crunched by three 49ers as he crossed the goal line.

Only twice during that sequence did the Rams dare run the ball. Both times Brown was stuffed.

“The more balanced you can be, the tougher it is to defend,” Stafford said.

He didn’t say it, McVay didn’t say it, Kupp didn’t say it, but, goodness, surely they all see it.

The Rams need a running back, or they are not running it back.