I agree with you but at the same time they have a relatively soft schedule, an easy division and a good quarterback. I'm not quick to call Rivers elite which it seems a lot of analysts have done, but if you look at his receivers he hasn't had that much to work with in his time. Plus he stepped in for Brees, an all-pro QB, and filled his role from the get-go.
Then you give them a healthy LaDanian who may have transgressed a bit but if you think about how great he was and his injury-filled season last year you have to view him as a top back in the league. Add that to Darren Sproles, a great change of pace from LaDanian who had a breakout season last year, and the Chargers running game stacks up nicely.
Receiving looks good also, they got a major boost from Chris Chambers but I still think Vincent Jackson is a number two receiver at best. Antonio Gates is the one who drives the passing game plus their running backs grab a lot of passes out of the backfield. Norv Turner was always better on offense and his gameplans will have them prepared.
On defense they keep most their major starters except Olshansky, get Merriman back and have a great talent in Cromartie so they'll at least (Chargers fans hope) be up to last seasons standards.
Add all that to a weak division and I see them making it to the playoffs. Beyond that I don't know.