These are tough times for Union Berlin mentally. It is not like they all can't play soccer, but it is the fear of failure and that turns into a cycle going on repeat mentally. But perhaps changing the coach could release some positive feelings and create new motivation. Since I would still count Augsburg towards the group of teams playing agains the relegation zone, this game is of high importance for Union Berlin. Actually, failure in this game is not an option. The least they should achieve is a draw.
It's hard to imagine why Union Berlin has slumped so deeply, even though they played in the UCL this season and the last two seasons were also solid. But their collapse is now real and very fast even though I think they will survive relegation but will not qualify for the European stage this season but it seems difficult to accept that in just a matter of seasons they have amazed us and in the near future they will also surprise us.
This reminds me of Leicester City, starting out ambitious and looking for big name players after they secured European football and wanting to aim higher, but ultimately struggling to stay in the top league. But I still have confidence that against Augsburg they have to get the three points, as you said, this match is important to motivate and raise the team's spirit which has been down. A draw is not good enough for Union Berlin because so far they have only won twice from eleven matches.