The Chargers have strong depth behind Rivers in Billy Volek and Jonathan Crompton, but Rivers is the engine in San Diego's offensive machine. He's coming off back-to-back 4,000-yard seasons and is the undisputed leader in the huddle and in the locker room. If he goes down with a serious injury, so do San Diego's Super Bowl aspirations.
With Rivers topping this list, it's only appropriate that his blindside protector fall next in line. McNeill is one of the league's elite left tackles and routinely faces the opposing team's best pass rusher with minimal assistance. Also boosting McNeill's importance is the fact that the other tackles on the roster -- Brandyn Dombrowski, Jeromey Clary and Corey Clark -- lack the skills to provide extended snaps on the left side of the line.
RB Ryan Mathews
The Chargers look to be stronger at running back in 2010, but they certainly aren't deeper. Last season's No. 3 running back, Michael Bennett, was never replaced, so if Matthews goes down the Chargers are left with Darren Sproles and little else. Given that the Chargers have been open in their opinion that Sproles is not a full-time back, they are gambling that Mathews will not be affected by the durability questions that followed him into the NFL Draft.
Gates and Vincent Jackson were the biggest beneficiaries of San Diego's full-on transition to a pass-first offensive attack. While both players are extremely valuable, only Gates makes the list because there is no one of the depth chart behind him who can come in and even come close to matching his productivity. The offseason departure of Brandon Manumaleuna puts even more pressure on Gates to keep himself healthy.
It's difficult to place a defensive back on this list, since the Chargers are deep in the secondary, but Jammer is far superior to his peers. If he goes down, Ron Rivera's cornerback corps will suddenly look very ordinary with Nathan Vasher and Donald Strickland both forced to log heavy snaps. Jammer is a shutdown corner and a stellar run defender, which more than makes up for his lack of ball skills.
Michael Lombardo is a member of the Pro Football Writers of America and a long-time contributor to the Scout.com network. His analysis has been published by the NFL Network, Fox Sports and MySpace Sports. He has followed the Chargers for more than 15 years and covered the team since 2003. You can see more of his updates by following him on twitter.