Anybody remember the old Street and Smith's College BB preview. And they would have pages dedicated to High School players and recruiting. It was the go to info before sites like these came about.
They used to have like 20 metro areas listed with their top 5 players, and up into the late 80's, Pittsburgh was included. But even then, you compared the 5 locals with say 5 from Cleveland or Memphis or Cinci (similar cities) and it would be much worse.
The one thing I can point to as a reason why, is Pittsburgh both city and metro area has a much lower African American population.
So say Cleveland has a metro area of 2.3 million and is 20%. Pittsburgh is 2.4 million and is 12% (These numbers are guesses, but I think fairly close).
Cleveland 460,000
Pittsburgh 288,000
So Cleveland has almost 200,000 more African Americans. Now not making this a race thing, but when 80% of the NBA is black and 70% of P5 starting lineups are black, this is somewhat significant.