We know that the level of competition in the Champions League is not easy even though Atalanta and Leverkusen hold the status of European League finalists. However, both teams have good self confidence, because they had achievements last season. This is different from other Champions League contestants, who managed to get tickets but did not win any domestic trophies. I think the strength of Atalanta and Leverkusen should be taken into account in the Champions League next season, they could be a surprise team, especially as their manager is still at the club. The squad depth of the two teams has not changed much, I think there has actually been an increase, this will be a good sign for them.
The most realistic target that Atalanta or Leverkusen can set is to reach the quarter-finals or semifinals, because I doubt they or any of them can reach the final. The Champions League will actually never be easy for anyone, mentality and experience determine everything there. Apart from all that, the presence of these two teams in the Champions League is an attraction in itself, considering that they had an impressive season last season. Everyone is curious about their performance next season, especially when they play in the Champions League.
Just because they won it or finalist, doesn't mean they will do fine. Look at Sevilla, they won previous season and then became fourth in their group. I mean that is a bad example of course because I think both Atalanta and Leverkusen should be considered better than Sevilla, that is true, but still, we are talking about a whole new level of talent when we move from Europa to UCL.
The best thing they could hope for would be going back down, but I think that is not a thing anymore, is it? This new system will take a while before people could actually get used to it, I am looking at it and seeing that it is not going to be all that easy, feeling like we are going to not know how the rules will work without living through the period.