SERAPIS,
Not necessarily. If Holmes and Forman weren't with the Sixers, would Smyth have had more minutes to offer Newley? Then would you see significant minutes available to returning players when the club already had Rychart, Nash, Newley, etc? Not necessarily.
Also, consider this: someone like Dench (I think he went to college, right?) might come back after four years and start at $50-100k. First four years in the US are $0. Then start the fifth at $50-100k.
Contrast that with someone playing locally. First year is capped at $25k or whatever it is. Within four years they will be at that same $50-100k level. They could have their degree or made inroads on it, be earning the same amount in the fifth year and have four years of earnings under their belt that a US graduate may not have. Both Oscar and Jacob have bought houses while in their first four years -- I don't know if they would have had that same opportunity were they returning from college.
It's a different experience, but not necessarily a lesser one. Look at Holmes -- 21-22 yo, has been starting for the team for a while, earns a good amount, has a house, is studying (I assume he still is) -- not much to complain about there!