The Carnegie Mellon Center for Economic Development is a great resource for exploring issues of migration. Their research demonstrates that inmigration is the problem facing Pittsburgh, not outmigration. The Pittsburgh region is remarkably inert. Between 1995 and 2000, no other large metropolitan area had a greater percentage of residents still living in the same house than Pittsburgh.
Higher educational attainment does correlate with inter-county relocations, at least if a job opportunity is the pull factor. The report cited above recommends that Pittsburgh target populations with postsecondary degrees. This bit of wisdom stems from a U.S. Census report titled, Why People Move. If people with graduate or professional degrees are going to move long distances, they tend to do so for a job.
In other words, the higher the educational attainment, the greater the labor mobility. As a result, knowledge workers tend to be economic opportunists. The irony is that Pittsburgh would have a better chance of attracting workers with advanced degrees than those without high school diplomas, but the region would also be more likely to lose knowledge workers once they get here. If you want to invest in attracting workers, target the less educated.