With McCaffrey out, 49ers’ defense needed to step up. Instead, it took a step back.

There was plenty of blame to go around in all phases for the 49ers Sunday in a 23-17 road loss to the Minnesota Vikings.

But as the 49ers embark on life without Christian McCaffrey, whether it’s three more games, twice that or longer, touchdowns are going to be harder to come by. Which means the 49ers defensively will need to step things up and go from being a simply good defense to one bordering on great.

Linebacker Fred Warner aside, they didn’t come close to that standard while seeing their record fall to 1-1.

“Defensively, when we say we’ve got to stop the run and be great on third down and we don’t do either of those things, it’s going to be a long day,” Warner told reporters. “We didn’t do anything to help ourselves in those areas, and obviously they played better than us.”

Life with McCaffrey has made touchdowns seem inevitable. Including the playoffs, McCaffrey has played 33 games with the 49ers and scored 39 touchdowns. You have to go back to Jerry Rice in his touchdown-scoring prime for anything close to matching it, and it’s worth noting that in two games without McCaffrey, the 49ers have had 19 possessions (not including a kneel-down) and scored only four touchdowns.

There was more good than bad in the Week 1 win over the New York Jets defensively. The inverse was true against Minnesota, with a crucial breakdown on a 97-yard touchdown play from Sam Darnold to Justin Jefferson and costly failures on third down, particularly late in the game after the 49ers had gotten within 20-14 on Jordan Mason’s 10-yard touchdown run.

In last year’s 22-17 loss in Minnesota, defensive coordinator-slash-scapegoat Steve Wilks took the heat for a zero blitz which resulted in a 60-yard touchdown pass from Kirk Cousins to Jordan Addison just before halftime. It was the beginning of the end for a coach who was let go after one year.

This time, with Nick Sorensen wearing the defensive headset, the 49ers dialed up a man blitz on Darnold at the 3-yard-line on second-and-9 after the 49ers —without McCaffrey, of course — failed to score despite having first-and-goal at the Minnesota 4-yard line.

Darnold, however, had enough time to get off a perfect deep strike to Justin Jefferson. Whether it was the design of the defense or an error in the secondary, Jefferson broke free from safeties Ji’Ayir Brown and George Odum.

“Just beat a man in coverage and they launched the throw and got it past the middle-third safety, which made it a house call,” head coach Kyle Shanahan said.

The touchdown put the Vikings up 10-0.

“We were in a man-coverage blitz,” Warner said. “I was one of the guys that was blitzing and I’ve got to get home and get some pressure on Sam. He’s able to step up in the pocket, deliver a great ball to Justin, and we’ve got to find a way to get him down right there.”

If that was the only transgression, the 49ers would have been fine. But their issues were written all over the stat sheet. Minnesota rushed for 146 yards on 24 carries, an average of 6.1 yards per attempt. The Vikings were 7-for-12 converting third downs while the 49ers were 2 for 10.

While Aaron Rodgers, coming off an Achilles tear, was stationary last week, Darnold presented challenges with his legs. He had 32 yards rushing on five scrambles.

Let’s face it: If Warner hadn’t stripped Aaron Jones after a reception at the 1-yard line which preceded a 99-yard scoring drive, or intercepted Darnold on a play that set up the 49ers’ other touchdown, the result would have been even worse.

Keep in mind, this is a Minnesota offense that was without not only Addison, but also tight end T.J. Hockenson, who’s out with an injury. And Jefferson, who caught four passes for 133 yards, left after being injured in the third quarter and didn’t return.

But within 20-14, there was still 10:16 to play when the Vikings took the field. All the 49ers needed was a stop.

Instead, Darnold converted an 11-yard throw to Brandon Powell on third-and-7 to the Minnesota 44. On third-and-8, Darnold struck for 26 yards down the seam to Jalen Nailor, with Yiadom unable to get turned around. That advanced the ball to the 49ers’ 28.

After chewing clock, the Vikings got to the 8 and Will Reichard kicked a 27-yard field goal with 3:30 left. At 23-14, that was essentially the ball game.

Warner said the loss “hurt my soul” despite finishing with nine tackles, two forced fumbles (one recovered by the 49ers), an interception and a sack.

Nick Bosa, who had his first two sacks of the season, was also critical of the 49ers’ play on third down.