Everyone is replacebale, but some more than others. Merriman had 12½ sacks a year ago and remains one of the most feared edge rushers in football. But how effective will he be playing on one leg?
Jyles Tucker is behind Merriman on the depth chart. How will that impact the team if Merriman goes down? Linebacker is the strength of San Diego's defense, one that led the NFL with 48 turnovers a year ago, 11 more than their closest competitor. That kind of production comes from pressure defense. That will still be there even without Merriman because the other linebackers are superior. The Chargers 3-4 front is anchored by one of the game's best nose tackles in disruptive Jamal Williams. The secondary has two superior corners in Antonio Cromartie and Quentin Jammer.
The offense has a great runner in LaDainian Tomlinson (1,474 yards and second straight NFL rushing title last year), a great tight end in Antonio Gates and a potentially great deep threat in Chris Chambers, who underachieved in Miami but is in a position to do some damage in San Diego. His partner, Vincent Jackson, actually played better than Chambers down the stretch and in the playoffs. But Chambers has big-play ability and enough weapons around him to allow Jackson to see some single coverage. The one concern is the departure of backup runner Michael Turner, whose explosiveness gave Tomlinson some plays off without the Chargers missing him. They have no such option this year.
On the hot seat
Quarterback Philip Rivers seemed to regress last season, throwing 15 interceptions while passing for 3,152 yards under new head coach Norv Turner. He no longer seems quite the sure thing he seemed to be and he must make clear he's the passer they thought he was when they let Drew Brees walk.
Difference-maker
Cornerback Antonio Cromartie had 10 interceptions last year to lead the NFL and key a defense that produced a league-high 48 turnovers. He played like an elite corner last season. If he does it again, he'll be one.
Hard road to hoe
The Chargers could put a firm grasp on the division in the first five weeks of the season because they open at home against Carolina, go to Denver, play host to the Jets and then travel to Oakland and Miami. All five are winnable games and a 5-0 start would make life difficult for the rest of the division.
Chargers will be better than you think if ...
Linebacker Shawne Merriman's knee holds up despite two ligament tears that will have to be surgically repaired at some point.
Chargers will be worse than you think if ...
Merriman's knee doesn't, because that means untested Jyles Tucker, a second-year player with 12 career tackles, would likely have to step in for one of the most explosive pass rushers in the game. That's a big step backward.