Talk dirty to me about zoning on Point Breeze Avenue

I've just recently started getting interested in city planning and land use regulation stuff - currently about halfway through Zoning Rules by William Fischel. I'm really fascinated by the trajectory of Point Breeze Ave and why its fate has been so different from East Passyunk. One thing I hear often is that the avenue is held down by poor zoning. But just at a glance, most of PBA is zoned to CMX-2, which theoretically seems like it should support a good deal of mixed-use development? Most of East Passyunk is CMX-2.5 or CMX-2 which seems identical except for a taller permitted building height and different setback requirements.

Obviously I know zoning isn't the whole story and that there are plenty of other factors affecting the area's growth - its relative isolation from the rest of the city, resistance by local politicians (Johnson) and residents, the fact that it's a relatively low-income and higher-crime area. Still, I'm interested to hear from anyone who knows about this stuff what role zoning specifically might have had in keeping Point Breeze Avenue from becoming more desirable.