MANKATO – Mike Zimmer's frustration with the unsettled safety position next to Harrison Smith finally reached its breaking point Sunday when the Vikings coach reached out and essentially pulled 34-year-old Chris Crocker out of retirement for a third consecutive season.

"At this point in my career, I really didn't want to go anywhere else," said Crocker, who played the past seven seasons with Zimmer as his defensive coordinator in Atlanta and Cincinnati. "I'm not starting over. I wanted to come here and play for a guy who has meant a lot to my career. I've given him everything I have. Just empty the gas tank and see where it goes."

Crocker signed a one-year deal worth the veteran minimum salary of $955,000. The Vikings released undrafted rookie defensive end Rakim Cox to make room for him on the roster.

Crocker might play as early as Friday's preseason opener against the Raiders. Although he admits he isn't game-ready, he has been working out regularly and knows Zimmer's defense well enough to coach his new teammates.

"I never retired," Crocker said. "You're always kind of ready, especially when you have a guy like Zim that you can play for. He said I could help these guys get better and also come in as a playmaker."

Zimmer had eight safeties on the roster before adding Crocker. Other than Smith, the group has been a disappointment that merited Sunday's transaction.

Injuries to Jamarca Sanford, Andrew Sendejo and Robert Blanton have dogged the position since Zimmer was hired in January.

Sanford, the incumbent, missed most of the offseason installment periods, while Sendejo sat out everything from the end of last season until coming off the physically unable to perform list and practicing in full pads Monday. Blanton was given the job to lose at the start of camp and then lost it four practices later when he pulled a hamstring.

Kurt Coleman, Mistral Raymond and rookie Antone Exum have seen time with the first unit in camp, but weren't good enough to keep Zimmer from reaching out to his old, reliable friend.

"I think I've been accountable, that's the biggest thing," Crocker said. "And he's just so honest. You really appreciate a guy who is going to tell you whether you're good or whether you're bad. At the end of the day, you know where you stand. I've always played at the highest level playing for a guy like that."

Crocker saw some limited action on Monday as Zimmer rapidly rotated safeties. In one segment, Zimmer changed the safety combinations four times in four snaps and five in seven.

Crocker has 554 tackles, 14½ sacks, 60 passes defensed and 15 interceptions in 151 games with five teams over 11 NFL seasons. Injuries in the Bengals secondary brought him back into the league for 13 games and nine starts in 2012 and for 12 games and three starts last season. The Bengals made the playoffs both years. Crocker had 37 tackles, 1½ sacks and two interceptions, including one for a touchdown, last season.

Crocker also spent the last two offseasons in the NFL's "Football Officiating Academy." But his dream of becoming an official was put on hold by yet another call from Zimmer.