Ok, Thanks. Sammy Lee published something quite similar. There have been hints that he is not popular in the German squad because of an arrogant attitude. Any truth in that from your perspective?
He has his buddies there with e.g. Özil and Draxler. In previous years he went into holidays with them. He might be a little bit too full of himself, maybe he was not "working" as much on the training pitch and following rules - but not one of this factors probably weighs enough as the one reason.
One factor that might have gone pro Brandt is maybe that with Tah and Leno already two of three players of the Leverkusen contigent had to go home. Tah was a non-brainer. Leno an understandable choice as the third keeper is in for the entertainment etc. and even if Trapp did not have much matches for PSG this season he had better matches for Germany and him and Ter Stegen used to have problems with each other in the U-teams.
---------------------
Just some more background explanation about that team
The rookie of the year of the EPL and big talent was left out might sound strange, but maybe it does not when you look at the German team.
It is build on a spine of the U21 winners of 2009 and the young players that were added in 2010 World Cup. All now play together with each others for 8 and in parts for more years. Kroos and Müller e.g. already played together in one Bayern youth team in 2006. Others already in U15 teams of the DFB. National squads come together far less than club teams - so playing together for a very long time or groups of players that play together in their club teams (like the spanish at Barcelona or Madrid, the Italians at Juve (ok, not a good example right now) or the Bayern players give a national team an advantage)
They already were the spine in winning the World Cup 2014 - even if the "oldies" like Schweinsteiger, Lahm and Klose were the team leaders and still had their roles.
Neuer (32), Khedira (31), Hummels (29), Boateng (29), Özil (29), Müller (28), Kroos (28) are now the spine - all of them but Özil are team captains. They have between 70 and 90 caps, a lot of experience for the national team and in their club sides were they won multiple national and international trophies. They are all now in their best age - but for some of them it will be the last World Cup. Know each other on the pitch and are friends off the pitch.
Maybe you understand than that it is certainly not this team that has to adapt to Sane's style but the other way around. Sane will get his chance when after this World Cup in the next years younger players will have to replace some of the older ones.
Kimmich took over from Lahm - first in the national team than at Bayern. His strengths are more in offense than in defense in difference to Lahm - but he has a personality that shouts future captain. Hector might not have the class of some others - but the left full back spot always was the Achilles heel for Germany. Werner has started to fill that striker spot that Klose left unoccupied. He already knows and tells that he has to go to a bigger club to make the step to World Class. Since Podolski lost his position on the left wing in 2012 we have seen various players fill in. Actually it always was Marco Reus' spot - but you know of his injuries. There was Götze, Özil, Podolski in last World Cup. Schürrle and recently Draxler who played on it. Right now it is better played with an inside forward with some playmaker attributes - that is why Reus and Draxler are ahead of Sane. Sane got various chances - yes, probably very seldom in a good setup with the first team players but that is how it works - but could not show his class in this environment.