90 your reasoning is a bit ridiculous. you're telling me that even though i have never played keeper before in my life, if i play keeper for my school because say our starter got hurt then i automatically become a great keeper? By your reasoning any starter at any school is considered good just because he is "obviously better than anyone else in his school" at that particular position.
Buffon any player can swing a game one way or the other at a crucial moment. True, a goalkeeper can have a large effect on a team's results and spirits, but i think you're giving all keepers a little too much credit. Some goalkeepers for good teams may only see 3 or 4 shots per game.
