It seems like we should be able to measure whatever effect there was. There must be sources of data about salaries in the Bay Area. Has anyone tried looking to see if there is a depression in tech workers' salaries, relative to people in other fields, during the time this agreement was in force?
You want to use other fields as a control? That makes little sense. From 2005-2009 the tech industry grew at a vastly greater rate than most other fields.