This isn't really complicated. The San Diego Chargers pass rush has been nonexistent (for a number of reasons) and the run defense hasn't exactly been great, either. There are a lot of guys playing hurt, or coming back from injury, and I'm sure that's factoring in a little bit. However, Tony Sparano is an offensive line coach first, so it makes sense that their offensive line play would get much better with him taking over as Oakland Raiders head coach for Dennis Allen.
The Chargers offense looks fine, although they haven't really been able to do much on the ground because they have stubbornly avoided running outside. The team should still be able to pull off a convincing win if the defense can find a way to make rookie QB Derek Carr uncomfortable in the pocket.