I think there's some truth to both sides of the coin, so to speak. You could be a very good poker player, and just get really unlucky for two or three hands in a row, and not really have any choice in the matter. Once this happens, however, if you let the frustration of being unlucky get to you, which is really easy to do, then you will start to run badly because you're frustrated and thus make more poor decisions, resulting in the loss of hands that you normally have much more control over and are able to often win.