Why do the 2100 blocks of Penn and Susquehanna suck so much?

A murder just three blocks from my home is getting me to ask this question.

I walk throughout Midtown, Olde Uptown, and the lower part of Uptown (Front to about 3rd) all the time and the 2100 blocks of both Penn and Susquehanna Streets are just not streets I would walk up. Ever. The 2200 blocks of either street (Penn, less then Susquehanna) are decidedly less sketchy and north of that they're generally alright.

However, just around the corner from the Governor's Mansion, is where this murder took place, and it's not the first one on either of these blocks since I've moved here. One block down are houses selling for the upper 100k. One block over is Uptown 2nd Street where houses sell in the 200k range. I just do not understand why the 2100 block of Penn and Susquehanna are so bad. Is it Section 8? Is there just not enough of a police presence? No sense of community? It boggles the mind to see such a disparity in just one block difference (by contrast, the 2100 block of Green which is between them seems like a quiet street. Again, it makes no sense.)