He can only play on the left hand side - the same side Reus and Draxler already play (and both preferred by Löw). The only right sided player they have other than Müller is Brandt, so he has to go and that basically leaves Sane without a spot. Sane has also never looked good playing for Germany and does not really fit the way the team plays.'
He's a great player, but Germany has a ton of great players and Löw has the balls to not bring people just people of their name recognition. Sane not going is something of a surprise, but maybe not a huge one. Löw did break German twitter this morning though, as Sane is a player that definitely divides opinion.