Olshansky is a big part of that D-line. His backup, Cesaire, is competent, but it's not the same, and against LJ it's definitely not the same. I'd say the Chargers D might be able to do alright against most RBs, but with a talented RB that can catch, the Chargers D is in trouble. If a healthy Westbrook was playing against the Chargers, he'd put up big numbers.
Right now the Chargers' D is nowhere near as scary as the beginning of the season. Fantasy-wise they aren't going to perform at the same level either.