So says media analyst John McManus in yesterday’s edition of “Perspectives” on KQED Radio. Bay Area newsrooms, including the San Francisco Chronicle and the San Jose Mercury News, lost one-third to one-half of its staff from seven years ago. That’s because while readers and advertisers have migrated to the web, dollars haven’t. Newspapers earned less than 6 percent of their total revenue from web ads in 2006, according to investment analyst Goldman Sachs. May was the worst month yet (in a non-recession period) for newspaper revenue.