The consistently bad franchises in the NFL have been bad specifically because they don't have a franchise QB. Comparatively, the Chargers had Brees and then Rivers, and yet haven't gotten far into the playoffs except for 2007.
That goes to show you how bad their front office is, when they can't surround a top 5/10 QB with enough pieces to have a deep run in the playoffs. Look at Roethlisburger and Eli comparatively - their teams were stocked with talent each time they won their respective SBs. The Chargers never really had that good of a cast, except for that small run in 06-08 with LT and a good defense.
It's unfortunate that Rivers will go down as the lesser of the 3 QBs in that draft class, even though he's had very comparable stats to both Roethlisburger and Eli, just never the same talent level to win it all