Needs more than one season for a trend to be seen, but it is quite noticeable how much of a closed shop so many of the leagues around Europe are now. Juventus, Bayern and PSG are almost guaranteed to win their respective leagues, and whilst Barca don't have quite such an easy ride, they still nonetheless win more often than not in recent years. I suspect that general lack of domestic competition does them no good when it comes to competitive games in Europe.