Inspection of the actual sales data would help us understand this graph better. Median price just means that of all the units sold in a given month, where was the middle? Some of the properties which fall into the attached categories don't qualify for FHA, or their HOA's may not meet lender's guidelines where reservers, rental/vs. owned ratios and HOA dues arrearages are concerned. When that occurs, cash offers may be the only option, depressing prices. While this graph looks drastic, keep in mind the price drop is $10,000.
As a buyer, think you have a lot of time to make a decision? This graph would indicate otherwise. On average, properties go pending in 3 weeks. Take into account those that require an appointment to see, and you'll conclude that homes in good condition and well priced sell at a much faster rate.
Pleasanton's supply in the attached inventory market notched up slightly, and considering the demand, that is most undoubtedly a good thing. That's just a 7 unit change though, so it may not have much of a ripple affect. According to this chart, sales were down while inventory is up.
When you compare the supply of March last year with the supply of March this year, and factor in last March's demand, then we are running a bit less than one month's supply. And that's far from a normal market supply.