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MANKATO – Anthony Barr admitted he can try harder than he did at times last season, which was a down year for the Vikings' talented linebacker.

Barr, entering his fourth NFL season, played a full season for the first time last year, but he didn't produce as much with career-low marks in tackles and sacks. He's a versatile pass defender and a wrecking ball in the Vikings' blitz schemes at his best. At his worst, he said his effort waned.

"It starts with my effort and picking that up," Barr said. "That's a big emphasis for me this offseason and I feel good right now."

He had taken a step forward in 2015 with seven pass deflections, 3½ sacks, three forced fumbles and an interception. His motor in a 20-10 win at Atlanta, during which Barr forced fumbles on both Tevin Coleman and Matt Ryan, gave a glimpse of his potential.

But those performances weren't frequent last season, even though the Vikings still ranked as one of the NFL's best in points and yardage allowed. Barr acknowledged he knows of games and plays when he wasn't trying as hard, but declined to be specific.

Barr's comments fall in line with criticism last year from head coach Mike Zimmer, who said the former ninth overall pick had a tendency to "coast" during games.

"We want to see consistency in play and be the impact player that you are," defensive coordinator George Edwards said of Barr. "One thing you can control is how hard you play."

No Reiff sighting

Left tackle Riley Reiff was not seen at the Vikings' morning walk-through or afternoon practice on Friday, a day after he suffered an undisclosed injury in the team's first practice of camp.

After practice, Zimmer said he didn't believe Reiff's injury to be serious, but the head coach did not elaborate. Reiff was at the facilities in Mankato, according to Zimmer. Tackle Rashod Hill filled in for Reiff on the left side during practice.

"I'm ready for Riley to make a speedy recovery," Hill said. "I check on him every day. I think he's still in the meetings and stuff."

Another D-II surprise?

Could the Vikings cultivate another Division II surprise? A year after receiver Adam Thielen's breakout campaign, Newberry's Edmond Robinson is trying to stake his claim in the Vikings defense.

Robinson, a former seventh-round pick in his third NFL season, has been switching off with veteran Emmanuel Lamur during practice to compete for the weakside linebacker job vacated by Chad Greenway.

"I think I've improved a lot mentally. I think I've always been a big, fast, strong, physical guy, but mentally I think I'm head over heels from last year," Robinson said. "May the best man win the job."

Koehn's range

Marshall Koehn could take Kai Forbath's job as the Vikings kicker if Koehn has a preseason as strong as his leg. Undrafted last year out of Iowa, Koehn figured he could still clear a field goal from deep despite forecast 10-to-15-mile-per-hour wind gusts this week.

"With this wind, I think 60 [yards] isn't out of the question," Koehn said.

Griffen's contract details

The Vikings are left with more than $13 million in cap space for 2017 after Griffen's four-year extension signed this week increased his cap number by $400,000 to $8.6 million. The team's current highest-paid defender, Griffen was fully guaranteed $18.8 million at signing, according to a summary of the deal obtained by the Star Tribune.

QB waived

Former Illinois quarterback Wes Lunt was waived by the Vikings on Friday. Lunt received a low-level guarantee of $5,000 to sign as an undrafted free agent in May. The Vikings signed former Stanford linebacker Noor Davis to fill out the 90-man roster.