Which ZIP codes and city neighborhoods in the Baltimore metro area had the most home sales? The biggest drops in price? The Baltimore Sun analyzed Metropolitan Regional Information Systems data to find the extremes during 2011, among places with at least five home sales during that period and in 2010. (A word to the wise: Big changes in average price are usually a sign of shifts in the sorts of homes selling — more foreclosures in poor condition, for instance, or larger houses. Individual homeowners' values aren't necessarily changing in lockstep.)