What’s wrong with the Warriors?

Spectators react to a foul against the Warriors during the second half of an NBA game between the Warriors and Oklahoma City Thunder at Oracle Arena, Tuesday, Feb. 6, 2018, in Oakland, Calif. The Warriors lost 105-125. less Spectators react to a foul against the Warriors during the second half of an NBA game between the Warriors and Oklahoma City Thunder at Oracle Arena, Tuesday, Feb. 6, 2018, in Oakland, Calif. The Warriors lost ... more Photo: Santiago Mejia / The Chronicle Photo: Santiago Mejia / The Chronicle Image 1 of / 12 Caption Close What’s wrong with the Warriors? 1 / 12 Back to Gallery

As head coach Steve Kerr took a seat amid a sea of media about to ask what’s wrong with his Warriors, he joked that Ted Koppel should be covering the story.

“Day 4, Warriors in peril,” Kerr said.

The standings suggest the Warriors (41-13) are still the grandest team in the land, but the reality is they’ve played far below par lately — and not just over the past four games, three of which they lost, including their first losing streak of the season.

Egad, two in a row.

The Warriors will try again Thursday night to energize themselves in a home game against the Mavericks, and Kerr is hoping it’ll start on the defensive end, collectively.

“We’ve got to claw our way back to becoming one of the top defensive teams in the league, which we’ve been for five years now,” Kerr said. “Over the last month, we’re one of the worst, so it’s pretty simple.”

In November, the Warriors ranked first in the NBA in defensive ratings. In December, they were second. Then came the new year, and they fell to 26th in January. February hasn’t started particularly well.

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Kerr cited the past 18 games, which don’t look bad on the surface, considering 13 were wins, but those wins came in a stretch in which the team’s defensive rating was near the bottom of the league.

“You’re not scrapping and clawing,” Kerr said. “We went 13-5, so we were fooling ourselves. It was all fool’s gold. We have enough talent where we can win games when we’re not playing at our best, but we’ve developed some really bad habits, and those habits are starting to be exposed, and now we’ve got to get rid of those habits.”

For example, better help defense.

Referencing the 125-105 loss to the Thunder on Tuesday, Kerr said, “One possession after another, we were just watching from the weak side and not helping. So you’ve got to really fight tougher.”

This doesn’t begin to address the Warriors’ recent issues with turnovers, three-point efficiency and technical fouls. Kerr said improved play in a single game — Thursday night’s, for instance — can help a team get back on track.

Even a single quarter.

Kerr recalled the Warriors dropping five of seven late last season. They were headed for another defeat, trailing the 76ers by 12 entering the final quarter, but permitted just 14 more points and rallied to win by two.

From there, the Warriors won another 13 in a row and closed the regular season on a 15-1 run.

“It felt like the sky was falling at Oracle,” Kerr said. “Everybody was shocked. We couldn’t get anything going on. We played a great fourth quarter and eked out a win. Sometimes that’s all it takes, a game or two where you really have to dig deep and defend at a high level. Competitive desire is the medication for something like this when you’re taking some lumps.”

Four games remain before the All-Star break: three in Oakland and one in Portland on Wednesday. All-Stars Stephen Curry, Kevin Durant, Klay Thompson and Draymond Green won’t get much of a break, but Kerr seemed confident there’s enough down time for all four to be rested before the schedule resumes Feb. 22.

Asked whether the team believes it simply can turn on the switch in the playoffs and cruise through the competition, Kerr shook his head and said it’s more a matter of letting their guard down of late.

“The lack of fight means not being really engaged,” he said. “It’s a fine line between winning and losing in this league, and I think we in some ways made it look easy the last few years for our fans and for ourselves, and sometimes that could bite you.”

John Shea is a San Francisco Chronicle staff writer. Email: jshea@sfchronicle.com Twitter: @JohnSheaHey

Thursday’s game

Who: Mavericks (17-37)

at Warriors (41-13)

When: 7:30 p.m.

TV/Radio: NBCSBA/95.7