Bayer Leverkusen underestimated Atalanta in that game, since Atalanta wasn't among the top 4 in the Seria standing before Europa League final, Leverkusen may think that it was going to be an easy game to win. No team will like to miss their chances of winning the Europa trophy. I stated on this thread before the match began, that we shouldn't be surprised if Bayer Leverkusen lost against Atalanta because that was the only opportunity Atalanta had to win a trophy this season, and Atalanta ended up surprising us by scoring two goals in the first half to end their unbeaten record. Of course, Xabi Alonso will learn his lesson this season, they shouldn't underrate any of their opponents next season, they should focus on winning their games.
Leverkusen this season has been quite impressive and certainly their performance has been really quite surprising, their journey in the European league is actually not too difficult in my opinion because from the beginning they only faced weak teams to be able to reach the semi-finals, the only difficult opponent they faced was of course Roma in my opinion, Atlanta did manage to beat Leverkusen, But I think it's not because Leverkusen has underestimated Atlanta, because as far as I know so far Alonso never underestimate about every opponent they face both in the league, DFB Pokal and Europa League.
The European league final is of course a breaker of their positive trend in maintaining an unbeaten record so far, Leverkusen can be said to have appeared quite confident in the match and of course previously they have prepared strategies, techniques and also game schemes that are considered to be able to beat Atlanta, but the opposite happened in the final match and Atlanta who had anticipated Leverkusen game of course performed better in the final, to be honest, I see Leverkusen performance this season is quite great but if we pay attention it seems that indeed their mentality in the final match is very small, the defeat to Atlanta proves that the mentality they have to win is not as big as when ordinary matches are played, besides that in the DFB Pokal Leverkusen only won with a score of 1 goal when facing a Bundesliga 2 team which they should have been able to win with a big score considering the performance and quality of the two teams that is much different.