A day after the Vikings’ fifth loss in the past six games, coach Mike Zimmer pinpointed a critical issue that is simple to say but has been complicated for this current offense.

“I would agree that we need to score more,” Zimmer said.

Just six offenses score fewer points than the Vikings’ 19.8 per game, and of those teams, only the Texans (6-4) have a winning record. The Vikings (6-5) cling to hope after their hot start but continue to suffer through a battle of attrition, particularly along the offensive line.

Zimmer didn’t have updates Friday on injured center Joe Berger (concussion) or right tackle Jeremiah Sirles (hip), but he assessed how a conservative offense needs to improve.

“When we’ve been successful on offense this year, because I just went back and checked all these things, our third-down conversion rate has been pretty good,” Zimmer said. “We’ve got to make a point of emphasis on that.”

The Vikings moved the chains on just two of 10 third-down attempts during Thursday’s 16-13 loss to the Lions. Quarterback Sam Bradford got the ball out quick and rarely threw beyond the first-down markers behind a patchwork offensive line, leaning on his receivers to make plays after the catch.

Offensively, the Vikings achieved one goal in keeping Bradford upright while nearly abandoning the league’s worst rushing attack. In a close game, Bradford took only three hits (no sacks) on 37 pass plays while handing the ball off just 16 times.

“Sometimes, some of these 3-yard throws are runs,” Zimmer said. “We’re trying to get a mixture of runs and throws in there, and we’ve got to do a better job on third downs obviously.”

A focus on defense, too

The Vikings’ defensive play in critical spots will also be a focus for Zimmer this week after surrendering another late scoring drive to the Lions in two losses this month.

Stafford orchestrated a 10-play, 68-yard drive that ended in a game-tying field goal, nearly three weeks after an 11-play, 87-yard drive defeated the Vikings in overtime.

“We knew exactly what they were doing,” Zimmer said. “We had a guy play coverage wrong, twice, and we had a guy take a poor rush angle. So, those were the three things. That’s what I’m talking about, executing in critical parts of the game.”

They still rank second in points allowed (17.5 points per game).

“But I would take 17 points a game every day of the week,” Zimmer said.

Kendricks grades well

Linebackers Eric Kendricks and Chad Greenway split snaps Thursday in Detroit. Kendricks was questionable to play because of a hip injury.

He didn’t look banged up, having a hand in three separate third-down stops by the Vikings defense. He tracked down Lions running back Theo Riddick for a 1-yard loss to force the Lions’ game-tying field goal in the closing minutes.

“He played pretty good,” Zimmer said.

RB Sankey signed

The Vikings added running back Bishop Sankey to the practice squad Friday.

Sankey, 24, was a second-round pick by the Tennessee Titans during the 2014 draft and was most recently with the Kansas City Chiefs this month. He was released by the Chiefs on Tuesday.

The University of Washington product averaged 3.8 yards per carry on 199 attempts during two seasons with the Titans.

Etc.

• Vikings defensive tackle Tom Johnson was fined $18,231 for his roughing-the-passer penalty at the end of Sunday’s game against the Cardinals.

• The two flagged hits on quarterback Sam Bradford, one apiece by Cardinals defenders Markus Golden and Patrick Peterson, were not fined.