Union Berlin was my favorite team this season and I was even hoping to see them at the top of the table and racing with Bayern Munich until last week when saw them having a bad performance because of having not enough potential for the rest of the season.
I think Union Berlin could have much better transfers and they could hire better players to help them in this situation.
Union Berlin was not ready to play for the German championship. They played a great season and nobody thought they would end up in the Champions League. They went far in the Europa League and also in the DFB Cup. They reached the quarter-finals there.
They will certainly strengthen themselves in the summer break and also finish in the top 6 next season.
Overall Union Berlin played a good game, but they have to improve again. Good play is not enough in a competition, they must also have a strong mentality to be able to provide fierce competition. This season, what Union Berlin has done, in my opinion, is enough, because they can show that they can be a big threat to other big clubs that have dominated the Bundesliga so far.
Instead, next season they should be able to play even better, but to be honest I'm quite worried that something bad could happen to them. We can see that from La Liga for example, the season before, Sevilla could play very well and even they put a lot of pressure on Real Madrid, but this season we see how they are in La Liga (I'm not going to comment on their performances in the Europa League). Yes, this season they played not as expected, you could even say they played badly.