Union Berlin this season seem to be suffering a fate that I personally can't tell the exact root cause but then the obvious looks like an effect from the change of coach, they seem to be yet aquinted well enough with this coach and his style so most players are still finding it difficult to cope but then they have still got good quality.
Leverkusen on the other hand continually keeps the maintaining their spot at the top of the league table with their points difference been a bit more that it was from Bayern Munich who happens to be the most fierce contender this season, it's quite interesting that at this point Bayern Munich is yet to be at the top of the table, which indicates that there's possiblity there could be a change in the leagues dominance this season.