Well said Skank, this is a national team and not a talent developing center. They should play for their respective clubs regularly before they get call ups.
Five years ago, Triantafyllopoulos, Iliadis, Katidis, Vellios, Diamantakos etc. were the promising players, like Limnios, Lamprou, Koulouris are now. Everybody can see where the aforementioned play now. Ages ago these talented kids were called Masmanidis (does anyone remember him? he was a youth team player in Germany), Koutsianikoulis, Fetfatzidis, Lampropoulos etc. So-called talented footballers often do not have a great career in Greece. Retsos plays at 19 for a Bundesliga team, everywhere in the world you can see youngsters are starters for famous clubs, he is the only real Greek talent now. There may be late bloomers (Holebas was one, and arguably Karnezis too), but these guys who are skilled and "look promising" while being on loan at 23 are probably new versions of Mavrias, Athanasiadis & co., what would mean they will never be useful at international level.