MANKATO – For the first year and a half of Antone Exum's Vikings career, the young safety had trouble convincing coach Mike Zimmer to insert him into the starting lineup. Finally, late last season, Exum got his shot after an injury to Harrison Smith.

But early in his second start, Exum suffered an injury, putting a quick end to his opportunity.

During the first quarter of a loss to the Seattle Seahawks in early December, Exum fractured a rib and injured the AC joint in his shoulder. He toughed it out and finished the game, but the Vikings soon placed him on season-ending injured reserve.

"It was hard, man. I try not to think about it and try to put it in the past," Exum said Thursday. "But that was definitely a huge opportunity for me. And for it to end like that, I was disappointed. But it's a new year and I used that to fuel me throughout the offseason. I'm just trying to earn a starting spot now."

Through the first week of training camp, Exum has taken a back seat to Andrew Sendejo and Michael Griffin, who have shared the first-team reps next to Smith, with Sendejo getting the majority. Exum has run with the second team.

"I'm feeling real comfortable out there," Exum said. "I'm healthy. I'm flying around out there. It's probably the best I've felt since I've been here. I'm able to not let my mind tie up my feet and I can just play off of instinct, but within the scheme, within what Coach [Mike] Zimmer and the coaches ask me to do."

Inconsistent play in practices and games is why Zimmer, who called Exum his most athletic safety other than Smith, has been reluctant to elevate Exum.

So has Exum, now in his third season, earned the coach's full trust yet?

"Sometimes," Zimmer said. "He's kind of there, and then he'll have a play that's like, 'What the heck are you doing?' So he's got to continue to [avoid] that."

Edge to newcomer?

During the first four days of camp, the Vikings gave newcomer Andre Smith and second-year lineman T.J. Clemmings two days apiece at right tackle. But for the second straight day Thursday, Smith, with the Bengals the past seven seasons, lined up at right tackle with the first-team offense while Clemmings, last year's starter, was with the second-stringers.

Zimmer cautioned, though, that he has not declared a winner in that battle.

"We haven't made a decision yet," Zimmer said. "We'll make it. I think we'll try to have something done after the day off on Sunday. But if we don't feel comfortable with it totally, we won't. But [Smith is] doing a good job."

Zimmer added that he likes what he has seen from Clemmings so far, too.

Maybe a special role

German speedster Moritz Bohringer has yet to make a positive impression on offense. But he has impressed special teams coordinator Mike Priefer with both his athletic versatility and his ability to quickly pick up the nuances of that third phase.

"We can do a lot of things with him," Priefer said of the 2016 sixth-round draft pick. "He's come a long way since the spring. He's very smart, and I think just learning the game of football, how we play it at this level, it's going to take him some time. But he has come a long way since when he first got here."

Bohringer will likely have to bring value on special teams to make the 53-man roster. He has been getting work as a gunner on the punt coverage team, as a halfback blocker on kickoff returns and in multiple roles on punt returns.

Ex-Eagles RB signs

The Vikings on Thursday signed running back Kevin Monangai and he practiced in the afternoon. The second-year NFL pro had three stints on Philadelphia's practice squad last season. The Eagles waived him in May.

With his signing, the Vikings' 90-man roster is full.