I do not know any Greek at all who was saying: "wow, the Greek team is better than the American one". Not a single. If you know some, then refer to them in your blog and not to a whole nation.
For the rest, yes I say "We" when I am talking about any Greek team, because they represent me. I could be in their position (had i had more talent and had I tried harder) and in any case, it is not only them. Almost every Greek National team in basketball is good. You can call them "they", I say "we". And I mean we, greeks, as a nation, have education and talent in basket, and this makes this "We" even stronger. Because under certain (certainly not freakish) conditions, me and/or you could be playing for this team. We chose a different way/job/hobby, but for example I was playing in the same team as Zissis (that you cited) and it could have been even me in his position.