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.
I don't understand what you mean, hasn't Union Berlin experienced a complicated season since the start of the season with coach Urs Ficsher? and even though their coach changed just a while ago, I think it's natural that the results are still the same as before because coach Nenad Bjelica also needs progress with the other players so they can adapt to the strategy he gave. It's not easy for Nenad Bjelica because he will be responsible for the results obtained by Union Berlin in the remainder of the season and at least being able to save Union Berlin from the relegation zone is already a good achievement.
The difference in points between Leverkusen and Bayern Munich is only 2 points and in my opinion that is not much because if Leverkusen suffers one defeat then their position will immediately be shifted by Bayern Munich. Leverkusen have been impressive this season and almost no team can stop them.
Yes it's true I also saw that Union Berlin had quite a hard time at the beginning of the season when Urs Ficsher was there and in addition there was a new coach who came, so of course I think Union Berlin's slump is still quite reasonable because of the new coach who certainly still needs a lot of time to be able to adapt to the players completely, I think this is a process, and for how long this adjustment process lasts I honestly don't know but certainly this is a matter of time, we'll see maybe next season Nenad Bjelica will really be able to apply all the formulas he has to the players as well while building chemistry for cohesiveness. And yes that's right, with Union Berlin now almost at the bottom of the table I hope Nenad Bjelica will be able to save his team a little to at least not end up in the relegation zone.
Xabi Alonso has quite a big responsibility in maintaining the performance and consistency of his squad, the threat from Bayern Munich does not play - play and at all costs Xabi Alonso must still maintain the position of his squad at the top of the standings, so the difference of 2 points I think it is still far from safe for Leverkusen, because if Leverkusen slipped in one of the next matches then obviously it was a golden opportunity for Tuchel's squad. We'll see if Leverkusen can be that strong.