NASHVILLE -- After spending OTAs and mini-camps installing and refining their new offensive and defensive systems, the Tennessee Titans hope to hit the ground running in their first training camp practice on July 26.

New coach Ken Whisenhunt has been busy installing a more up-tempo, pass-friendly offense that might finally bring the Titans into the 21st century on that side of the football, after years of a plodding ground attack run by both Jeff Fisher and Mike Munchak.

Quarterback Jake Locker hopes this will help pump some needed life into a career that has been pock-marked by debilitating injuries since becoming a starter in 2012. He missed five games with a shoulder injury two years ago and last season missed two more with a hip injury before a foot injury shelved him for the final seven games. In all, he has missed 14 of a possible 32 starts.

While the Titans are giving the 2011 first-round pick one more chance to stay healthy and deliver, they have hedged their bet by declining his fifth-year rookie option and also drafting strong-armed former LSU quarterback Zach Mettenberger as insurance beyond this season.

It means that Locker is on the spot to stay healthy and play himself into the Titans' long-term plans. And even though new coach Ken Whisenhunt didn't draft Locker, there is the prevailing feeling that the quarterback will be given a fair shot to prove himself.

Still, there is little doubt that Mettenberger will make it. Some feel the strong-armed rookie will prove to be a steal.

The Titans must make a decision one way or the other on Locker, whose contract is up at season's end. Mettenberger will get a year to sit and learn and allow his surgically repaired knee to fully heal, and if the Titans feel they need to move on from Locker after the season, Mettenberger could get the first shot in 2015.

Mettenberger credits the medical crew that performed his reconstructive ACL surgery for getting the Titans' rookie quarterback on the field and healthy miles ahead of schedule.

Mettenberger said doctors who did the surgery in January did the procedure differently than the way some knees are reconstructed, using a hamstring graft instead of a patella graft.

"At LSU, we do a different kind of surgery. We used a hamstring graft instead of the patella. The healing process on that is a little faster than the patella," Mettenberger explained. "We've had running backs and receivers come back after four-and-a-half months and start practicing with the team again.

"Obviously, I'm not a running back and I don't have to run and cut as much as those guys, but I was able to come back in three months and do my pro day and do that efficiently. At four months, I was really expecting to be able to practice, and I've been doing so. I always had this in my mind to be ready after four months, and now that that's come and gone, it's all about progressing and getting back to 100 percent."

Mettenberger will stay in Nashville to continue his rehab work this month. He will focus on increasing the strength of his hamstring and quadriceps muscles around the surgically repaired knee. He hopes to be able to push for playing time this season, too, but the coaching staff indicates that might be a bit ambitious.

"Structurally it's 100 percent. It's just the strength of my quad and hamstring that I've got to keep developing. By training camp, I should be much better," Mettenberger said. "I think I showed everyone that I was moving pretty well being five months out of surgery. It's just going to be about continuing to work hard and when training camp comes, I'll be further ahead than I am now."

Whisenhunt said Mettenberger will start low on the depth chart as veteran Charlie Whitehurst, signed away from San Diego in the offseason, will be Locker's top backup.

Former Arkansas quarterback Tyler Wilson is also on the roster.

Whitehurst was signed in part because he knows Whisenhunt's offense, as they were with the Chargers last year. However, being behind the durable Philip Rivers in San Diego has Whitehurst a bit rusty. He last threw a regular-season pass in 2011.

"Charlie is the No. 2. That's why we signed Charlie to come in here. He'll be that way going in (to training camp)," Whisenhunt said.

Asked if Mettenberger could move past Whitehurst in camp, Whisenhunt said, "I think you never say no to any of that. You've seen rookies do it before. It's hard to say when we haven't seen anything of Zach in pads or live action. We'll have to see how that plays out, but I want to make sure I'm clear -- Charlie is our two."

Defensively, the Titans are shifting to a 3-4 under new defensive coordinator Ray Horton, who has been busy sorting through the personnel he inherited and the free agents and draft picks acquired to see who fits as outside linebackers, nose tackles and five-technique ends.

Beyond the offense and defense, there is an unusual situation on special teams, where kicker Rob Bironas is gone after nine years and the job open.

Maikon Bonani is back in camp for the second straight summer. Bonani showed a strong leg last year, but had some accuracy issues. His primary competition will be free-agent rookie Travis Coons, who had school obligations at the University of Washington and missed the team's OTA work.

Lack of depth is causing concern at wide receiver, where there is talent at the top of the depth chart with shifty Kendall Wright in the slot, and steady Nate Washington on the outside. Justin Hunter also has big-play potential. But after that, there are just unproven names.

Michael Preston, a former practice-squad player, has 10 career catches. Marc Mariani, a former Pro-Bowl pick as a return man, has just five catches and has spent the past two seasons on injured reserve. The Titans added Brian Robiskie, who failed to produce elsewhere. So Locker hopes to find a couple more reliable receivers to help him in Whisenhunt's new offensive system.

Here is a snapshot of the Titans' roster as they head to training camp:

--QUARTERBACKS: Starter - Jake Locker. Backups - Charlie Whitehurst, Tyler Wilson, Zach Mettenberger.