As a DTS voter it makes sense. A lot of people in these well to do areas in the Bay Area, the beach cities, north SD and parts of OC to a certain extent are socially liberal but don't feel totally comfortable with Democrats on everything. They will maybe vote for the Democrats because they hate the Republicans more but at the same time vote no on all taxes. And in years like 2010 they might vote Republican. I didn't vote Republican in 2010 but I did vote no on all taxes.
The wave sort of missed California in 2010.
If you look at the Boxer-Fiorina race, the swing back from Obama was 14 points which is the same as the nation. And the areas that swung back the most are the ones I mentioned.
The Democrats picked up the governor's seat, another statewide office, and increase their members in the state Assembly to a 38 year record, and none of the 66 Democrats to go down in the House was in California. A wave may have hit California in 2010, a small Democratic one.