NASHVILLE, Tenn. -- The Tennessee Titans waived safety Robert Johnson on Sunday after he failed a physical and added a pair of veterans to add depth at linebacker and safety.

Johnson was a fifth-round draft pick in 2010 out of Utah, and he had his best season in 2012 playing in 12 games and starting three before hurting his foot and being placed on injured reserve Dec. 4. He spent the offseason recovering and was on the physically unable to perform list in training camp before being waived.

Coach Mike Munchak said Sunday night that Johnson couldn't stay healthy and hopefully will get an opportunity elsewhere with different luck.

"I think it's just been frustrating for him too, and us, that injuries have been unfortunately for him since he's been here," Munchak said. "He hasn't been able to stay healthy. Great kid loved having him here I know he loved it here too. He had a great opportunity last year, worked hard to get it. Had the injury. Tried to come back and still not healthy. We needed to have someone at that position who could help us."

The Titans also waived defensive end Thaddeus Gibson to make room for linebacker Gary Guyton and safety Cory Lynch.

Guyton has played five seasons with New England and San Diego. Lynch has played for Cincinnati, Tampa Bay and San Diego.

Notes: Jake Locker had his worst practice of camp Sunday night. The Titans quarterback was intercepted three times -- twice by Bernard Pollard -- and got lucky when linebacker Moise Fokou dropped what would have been a fourth in the end zone. Munchak defended his starting quarterback's struggles. "I just thought the offense struggled today in periods," the coach said. "We had a lot of different periods trying a lot of different things, and the defense made some good plays."