SAN DIEGO – After playing at an MVP level through the first six games, Philip Rivers limped to the finish line for the San Diego Chargers in 2014. But at 33 years old, Rivers still has productive years ahead of him. With Rivers in the final year of his contract, one of the main storylines heading into training camp will be the Chargers working to get a contract extension completed for the North Carolina State product.

Philip Rivers propelled the Chargers to a 5-1 start last season before his protection broke down and he got banged up. Patrick Smith/Getty Images

Lock: Rivers, Kellen Clemens

On the bubble: Brad Sorensen, Chase Rettig

The good: Although speculation had Rivers moving on in a draft-day trade, the Chargers never had any intention of trading the team’s franchise quarterback. Rivers is durable, serves as the face of the organization and sets the tone for everyone at Chargers Park with work ethic and no-nonsense demeanor. Along with all of that, Rivers can still play. Through six games last season, Rivers completed 69 percent of his passes for 1,756 yards, 15 touchdowns and just two interceptions, posting a league-leading 117.6 passer rating. The Chargers were 5-1 in those games. But San Diego’s protection unraveled during the second half of the season with the team cycling through five different centers, resulting in Rivers suffering back and rib injuries that affected his play. Clemens, 32, can win games in a pinch and is one of the top backup quarterbacks in the league. Sorensen has looked more comfortable in his second stint with the Chargers. And Rettig, a signal-caller out of Boston College who went to training camp with the Green Bay Packers in 2014, showed off a strong arm during offseason work.

The bad: Rivers is in the final year of his contract, scheduled to make $15.75 million in 2015. So far, he has balked at signing an extension, suggesting that he might not be thrilled at the possibility of relocating his family should the Chargers move to Los Angeles. With some key players such as Nick Hardwick retiring and Eric Weddle not being offered a contract extension, Rivers also wonders if the Chargers have enough pieces to compete for a Super Bowl. General manager Tom Telesco said the team wants Rivers to retire a Charger. Rivers likely will remain with the team beyond 2015.

Bottom line: The Chargers have to do a better job of protecting Rivers. He was hit or under duress on 114 dropbacks in 2014, the 12th most in the NFL. The addition of Orlando Franklin, Joe Barksdale and Chris Hairston in free agency along the offensive line means Rivers should be better protected. With Danny Woodhead returning and the drafting of Melvin Gordon, the Chargers should be more balanced on offense. Most important, Rivers says he’s healthy. “I feel good,” Rivers said. “It’s a long way from how I felt in December. I have no issues.”