Have Bayern Munich, Barcelona, Real Madrid entered into a league of their own?

There is obviously a separation between the great clubs and the good clubs in European competitions this days. However, the questions must now be asked if we're seeing a gap forming now between Europe's elite clubs and their peers.

The question first came to my attention over the weekend when Jose Mourinho was discussing how he believes Bayern Munich, Barcelona, and Real Madrid have established themselves most powerful of all the big European clubs.

"I think there are only three clubs in the world who have the power to say, 'I don't sell'. This is Real Madrid, Barcelona and Bayern Munich. Is anyone in England interested in Thomas Müller? For sure. Can we, England, bring Thomas Müller from Bayern? I don't think so.

"Does anyone want [Lionel] Messi? Can you bring him? I don't think so. They are big clubs with big history, economically strong and stable, income amazing. I think they sell when they want to sell. When you see a player leave one of these big clubs you have to think it's because they want him to go. That's my feeling. [I'm] speaking about the ones who make the world stop. Big transfers. When does Messi leave Barcelona? When he finishes his career."

While everyone knows about the off the field powers that these clubs have become, the results on the field have shown in recent years, too. All three clubs have made it to the Champions League Semifinals in each of the previous four tournaments, and each of them have won one of the last three Finals. The Silverware followed. They have won twenty trophies between them in the last three seasons alone.

Mourinho is not the only one that feels this way. Wolfsburg manager Dieter Hecking revealed as much this week when talking about the potential transfer of Kevin De Bruyne to Manchester City.

"You never know what will happen. We consider every offer. Kevin will only be allowed to leave the club should we receive an extraordinary offer."

"Despite all my appreciation for Manchester City, it would be completely different for me if Real Madrid, Bayern or Barcelona were going for him. I'd understand everything then."

So, the question remains: Have Bayern Munich, Barcelona, and Real Madrid left their European peers behind?