MANKATO – The chances for DeMarcus Love to make the Vikings' 53-man roster might have gone out the window Thursday when the NFL hit the third-year offensive tackle with a four-game suspension for violating the league's performance enhancing substance policy.

Love said the positive PED result surfaced in April from a test he took in February or March. He quickly appealed but was denied, resulting in Thursday's announcement.

The offensive tackle wouldn't reveal the banned substance he tested positive for but said it was in a supplement he was taking.

"I was shocked, man," Love said after Thursday's practice. "I've never cheated and never will. Not intentionally. Unfortunate it's something I can't change. It happened. It didn't work out in my favor, and so I've got to face the consequences."

Love will be allowed to continue practicing throughout training camp and is cleared to play in preseason games. And if he makes the 53-man roster, he'll be suspended through the Vikings' Week 4 game in London.

A sixth-round pick out of Arkansas in 2011, Love has yet to play in an NFL game. He was inactive for all 16 games as a rookie and missed last season after tearing a pectoral muscle during training camp. His latest setback, however, is undoubtedly the worst.

Said coach Leslie Frazier: "I let him know my displeasure and our entire organization's concern for him. Hopefully he'll learn something from this and grow from it."

Punt return auditions

The Vikings aren't exactly in a desperate search to find a punt returner. The man who's held that role for the past two seasons, 25-year-old cornerback Marcus Sherels, continues to impress the coaching staff with his reliability.

But when roster cuts begin later this month, so many dynamics will be at play that special teams coordinator Mike Priefer continues to eye other options. Among the horde of players also hauling in punt returns at camp: Josh Robinson, Jarius Wright, Joe Webb, Cordarrelle Patterson, Jerome Simpson and Adam Thielen.

Determining just how close the competition is, Priefer said, will require preseason game action to evaluate.

"Right now, after a week of camp, I would say [Marcus] is the front-runner," Priefer said. "But I'm always looking for people. Because you never know. Is he going to be there on game day? Is he going to get hurt? Things happen in the game. So I have to have my ducks in a row."

Last season, Sherels averaged 9.0 yards on 32 returns, broke off a 77-yard touchdown in a Week 4 victory over Detroit and fielded 59 punts without losing a fumble.

"It's one of those things where you trust him catching the ball," Priefer said. "He tracks it, he catches it very, very well and he makes the first guy miss most of the time. … I trust him. Our head coach trusts him. And our team trusts him."

Full of energy

As a matter of principle, top draft pick Sharrif Floyd is still stuck down the Vikings' depth chart at the three-technique tackle position. But he's quickly showing why he'll be a major presence once the season starts.

Floyd had two particularly impressive run stops during 11-on-11 work on Thursday, blasting running back Jerodis Williams in short yardage action, then drilling Bradley Randle for a loss near the goal line.

Said Frazier: "I like his passion. For a young guy to love the game as much as he does and have his athletic ability [is impressive]. … He's one of the hardest-working rookies you'll ever see. To have the talent combined with that work ethic, you've got a chance to be a pretty good player in our league."

Etc.

Linebacker Erin Henderson left Thursday's practice briefly because of a sore groin but was able to return. The Vikings will keep a close eye on Henderson in the days ahead.

Audie Cole filled in at middle linebacker with the first team during Henderson's absence.