I'll take my blue specs off and admit that (for now) there are 3 giants of the football world. Real, Barca and Bayern.
To leave any of those, it's because of a player not feeling wanted or due to a falling out with the manager. Muller is wanted and is performing well. To leave for us, Chelsea, PSG, Juve etc, would be seen as a backwards step at the moment.
To leave and join someone like utd, seville, fenerbace, lyon etc, just wouldn't make sense.
To leave any of those, it's because of a player not feeling wanted or due to a falling out with the manager. Muller is wanted and is performing well. To leave for us, Chelsea, PSG, Juve etc, would be seen as a backwards step at the moment.
To leave and join someone like utd, seville, fenerbace, lyon etc, just wouldn't make sense.