I'd be really curious to know how San Francisco rental prices are diverging between newer (not rent controlled) buildings and older (rent controlled) buildings. There is historically not as much turnover in the rent controlled buildings, and people pay a premium price at the time of move in because they get protection from rent increases. I would guess that rent controlled unit prices did not slip that much because people realize that San Francisco will be a great place to live at some point in the future. These rental surveys are heavily biased towards larger, newer apartment buildings.