MANKATO – Jamarca Sanford has been through battles like this before and emerged victorious. But here we are at another training camp where Sanford, a Vikings starter in 2012 and 2013, appears to be on the outside looking in of a competition to start at safety.

"It ain't nothing new," he said. "New coaches or old coaches, I've been competing every year since I've been here."

Sanford missed most of the spring workouts because of an injury, in the process missing an opportunity to make an impression on new coach Mike Zimmer. His absence enabled Robert Blanton to step into the spot next to fellow safety Harrison Smith. Blanton started training camp with the first unit, while Sanford, finally cleared to resume practicing, found himself running with third-stringers.

An injury to Blanton has again opened the door at the position, and Zimmer has auditioned Sanford, Mistral Raymond and even rookie Antone Exum over the past few practices. Sanford seems to be on the rise in the eyes of Zimmer's coaching staff, but he said, "I'm not worried about where I stand."

Zimmer has said that preseason performance will carry extra weight at the safety position because there is typically little, if any, live tackling during camp practices. Zimmer wants reliable tacklers in the secondary because few things make him cringe more than yards after the catch.

Sanford is cool with that. He believes he will rise to the top once the safeties can actually hit somebody.

"You can make plays in practice but not make them in the game," Sanford said. "At the end of the day, it's about what you do in the games. I'm looking forward to the preseason and making plays."

As for Blanton's injured hamstring, "I don't know how long it's going to be, honestly," Zimmer said again.

GM quizzes coach

Zimmer met with General Manager Rick Spielman for an hour Saturday to dissect a handful of in-game management situations. Zimmer said Spielman gathered tape of different scenarios, looking at such things as when a coach should or shouldn't call a timeout, throw a challenge flag or kick a field goal.

The two will meet again each of the next four days, tackling 15 different in-game situations as Zimmer prepares for his first preseason game as a head coach Friday against the Oakland Raiders.

So how did Zimmer fare in Spielman's first quiz?

"Rick is never wrong," Zimmer said with a smile.

Yankey not ready yet

Throughout camp, the Vikings have stuck with the same five offensive linemen who started for them during the 2012 and 2013 seasons. Zimmer said he thinks continuity is key for that group.

"It's extremely important that those guys work together all the time," he said. "When you're not on the same page, you're letting Adrian [Peterson] get hit when he doesn't need to, you let the quarterback [get hit]."

The team is high on David Yankey, a fifth-round draft pick from Stanford. But he missed much of the spring workouts due to an NFL rule. Zimmer said Yankey is not making many mental mistakes but believes the rookie needs to refine his technique to be considered a candidate to start this season.

Etc.

• Rookie tight end AC Leonard was spotted Saturday for the first time since he left Wednesday's practice because of what Zimmer initially described as a headache, though Leonard did not practice. Zimmer said after the morning walkthrough that the Vikings, still are trying to get a handle on what is ailing Leonard, have one more test to put him through before disclosing a diagnosis.

• Cornerback Josh Robinson was sidelined for another practice because Zimmer believed it was best to hold him until after Sunday's off day to give his hamstring a little bit more rest.

Star Tribune staff writer Master Tesfatsion contributed to this report.