I really do believe that there is such a thing as losing cultures in sports, and that it takes more to ultimately win championships than just having some good/great players. Don't get me wrong, you need good/great players to win championships. But not every great players is able to win one, either. He has to have the right team and culture around him to do so.
I have heard too many players and executives (in the NHL, NFL etc) talk about the importance of culture over the years to believe it's made up.
From my own experience playing sports, the best teams I played for almost always had one thing in common - what I would call a "good team culture". It almost always started with very good coaching and the best player(s) on the team being bought in and helping push the coaches message. The first year I won a league championship with my team, we had a bunch of good players but we also had a great team culture. We all had a lot of belief in what the coaches were doing. There was a great attitude during games and practices. Even when we were down in games, we always believed that we could come back and win. There wasn't that pouting attitude or any giving up. Not every team that I've been on with good players had this. Having the right mix of personalities with the right attitudes is a significant thing IMO.
I've also played on teams with some really talented players that ended up losing quite a bit and there was a noticeable difference in the coaching and/or player attitudes & belief system on those teams. When you have talented players who don't give a crap or start to pout when losing, or don't buy in to that team, it's usually not going to end well, IMO anyway. Like this one year we had a few really talented players (and what I considered to be a good team overall) but the best players were kind of jerks that formed their own little clique in the locker room and were always talking crap about the coach as well as some of their teammates and it really had a major impact on the entire team. We never won nearly as many games as we could/should have. As soon as we'd get down in the game the entire demeanor of the team changed.