That said, I think the degree holders were better candidates usually, but I strongly suspect it wasn't because of the education. Colleges attract people who are good at carefully following complex instructions, have a healthy respect for authority, and can delay gratification in the extreme. They are also experts at navigating a system from within. The degree acts to filter out people who are too independent to fit well within a hierarchy.
I don't think I ever noticed much difference between different kinds of degree holders aside from a broad separation between analytical degrees and humanities degrees, which again might have had more to do with the initial filter than anything taught in the classes.