MANKATO, Minn. (AP) — The lack of production from the Minnesota Vikings' rookie class as one of many factors that contributed to the team's disappointing 8-8 finish last season.

In hopes of helping this year's class of first-year players make more of an impact in the upcoming season, Vikings coach Mike Zimmer decided to call them in early for the start of training camp. The rookies reported with select veterans Sunday, four days before the full team is required to report.

"I just felt like we wanted to try to get them up to speed as quick as we can," Zimmer said. "Last year a lot of the rookies didn't play as much as they had in the past. I just figured, let's give these guys every opportunity we possibly can to get them up to speed a little quicker."

Last year, first-round receiver Laquon Treadwell had just one catch for 15 yards, second-round cornerback Mackensie Alexander was underwhelming in 13 games and fourth-round offensive lineman Willie Beavers was released before the start of the season, cleared waivers and was brought back to the practice squad and played just 11 plays in two games.

Much more is expected this season out of second-round running back Dalvin Cook and third-round center Pat Elflein, both of whom are in the mix for starting spots. Linebacker Ben Gedeon, a fourth-round pick out of Michigan, could be in the mix as well, and the Vikings have taken extra steps to make sure the youngsters are acclimating to their new surroundings in a hurry.

Zimmer estimated the rookies had 10 more practices than the veterans did in May and June, all in an effort to help them digest new playbooks and learn new systems from the ones they played in during college.

"With the way the NFL is going now with younger and younger players, I just thought it was important," Zimmer said. "Hopefully, a lot of these guys will be playing."

The younger Vikings will have three practice days before the full team reports. The team is in the 52nd and last season of holding its training camp on the campus of Minnesota State University, Mankato, about a 90-minute drive from the Twin Cities, so the extra time will help the rookies get to know their way around the complex before the hectic full-team workouts get going.

"I am feeling everything out. My teammates are making me feel real comfortable and I just think the unique thing about this situation is that we have some good vets that welcome everybody with open arms," Cook said. "They are doing a great job of that and they are making the rookies feel real comfortable, so I am pretty comfortable with my situation."

Running back Latavius Murray is one of a handful of veterans to show up early. Murray missed the entire offseason program with an ankle injury, so he wanted to get here early to try to start making up for the missed time.

"I think the fact that they'll have a few days before everyone else comes back into the offense and defense will be very helpful," Murray said. "It'll be helpful for me just being here. I'm happy to be able to dive back into the playbook, and again, I want to learn it as much as I can, inside and out, so when I'm back on the field I'm able to play fast."

Zimmer will be testing a few things out himself. He missed two weeks earlier this summer while recovering from an eighth surgery on his right eye to address a detached retina. He said Sunday that a gas bubble placed there by his doctor to hold the retina in place has finally dissolved, giving him clearer vision for the first time in months. Zimmer is able to wear a contact lens in the eye now and is hopeful that the problems of the past year are finally behind him.

He was also able to fly from his ranch in Kentucky back to the Twin Cities for camp, another sign that things are progressing.

"My vision is much better," he said.

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