I'm stealing the first map from Chris Briem at NullSpace and it is a representation of the percentage of votes by precinct that Luke Ravenstahl won in the 2007 general election.
As you can see here, Ravenstahl's only significant areas of weakness were in the Strip District and the East End. Eyeballing the East End, it looks more like the Centre Avenue/Baum Boulevard corridor served as the northern boundary with the exception of a precint in Bloomfield to the north, and then most of the 14th Ward in Squirrel Hill, Regent Square, Swisshelm Park, Point Breeze. The rest of the city Ravenstahl dominated with minor exceptions.
This second map is from the Angry Drunk Bureaucrat. It looks at the 2005 Democratic Primary which Bill O'Connor, the deceased mayor won by basically doubling up on both Bill Peduto and Mike Lamb. This map looks at where progressive activist hope, Bill Peduto, City Councilor for most of the East End did particulary well in the 2005 primary.
Notice how the two maps matched up reasonably well in the East End, and parts of the Southside and Mexican War Streets. I have not run the model yet, but I would bet you that 2005 % of vote to Peduto is a strong predictor of the 2007 DeSantis Vote by precinct. If this suspician is true, than we can tease out a couple of interesting things.
1) The swing voter in Pittsburgh politics is most likely a good government-type, college educated individual with a decent job. Bill Peduto has been able to attract this swing voter fairly effectively but has not been able to build off of this swinging base (at least at places other than Cappy's) into an effective power structure.
2) Even after spending 20x as much money than the previous GOP nominee, there is little chance of a viable coalition for the GOP to win in the city.
3) Liberal/Progressive activists are functionally irrelevant at the municipal and county-wide single member district level. DeSantis picked up decent support from this group, but barely deviated from historical expectations of GOP vote share. I wrote about this problem in early October:
The 2009 race will probably get started in the next couple of weeks as Ravenstahl has two more years to pull on enough rope to hang himself poltically, and a lot of people who were productively non-productive in this cycle are starting to stretch out and warm up their political muscle for the next run. However we should remember that the progressive activist groups in the city that threw some weight behind DeSantis on the individual member level will have a loud voice but minimal real impact.
Throwing in significant progressive support to a candidate who will beat historical trends if he gets 33% of the vote in the general election AND who will not support progressive ends on a consistent is folly. It throws away significant credibility of being team players and electoral reliability, and marginalizes the perception of impact and power of the progressive activist base if DeSantis performs to near normal GOP performance within city limits.....strategic competence suggests many actions other than public and ineffectual defection......If a group is going to defect and fail to achieve any meaningful impact on anything, then it should not be surprised when it is marginalized in the future.