"are looking at 20 - 30 percent declines in value and cash flows are declining as renants take advantage of a rentors market"
Now isn't that an oxymoron? Value and cash flow are supposed to go hand in hand. An asset's value is usually based on the cash flow it presents times a certain multiple. In real estate it's divided by an expected rate of return based on the market.
Commercial real estate values are down because of a decline in cash flow. What is the property worth now with current cash flow and how much can I borrow and still cover the debt service without defaulting on my loan covenants.
Residential real estate is more dependent on jobs, supply, and musical chairs.
Read the writing's of Bond guru Bill Gross. He says we have relied to much on asset appreciation spurned by increased leverage than by GDP or cash flow.