As is often the case, I think some topographic maps can help illustrate the fundamentals of Pittsburgh neighborhoods. So here is the East End:
And here is what I think more or less explains the fundamental appeal of East Liberty:
That circle is roughly between the Allegheny River and Forbes, and the Hill and Braddock, and basically within that circle, East Liberty historically was the undisputed epicenter, as reflected by the pattern of the main roads. And arguably you could also extend it further east along and around Penn, but at some point you run into Downtown Wilkinsburg being an historic (and hopefully future) rival, so I think Braddock works as a rough border.
And just to pile on the grounds for optimism--there is currently a lot of underutilized land in that circle, including in East Liberty itself, Larimer, Homewood, the Baum-Centre corridor, and Garfield. There are projects of various sorts in the works in all those areas, and I think there is a clear positive feedback cycle going between the redevelopment of those areas and the redevelopment of Downtown East Liberty.
In short, as I have suggested before, you can't really grasp what is happening, and what could happen, in East Liberty if you think of it as just another neighborhood. What we are witnessing is rather more like the rebirth of a new small city, with its own Downtown and a variety of satellite communities. And all on a scale that could actually make Greater East Liberty, seen in this way, one of the most important small cities on this side of the state. Which it basically used to be.