Defeat in the Europa League final can also be valuable lesson that anything can happen easily, they can use incidents like this as reference for enthusiasm for next season when competing in the UCL.
Yes, their defeat in the Europa League final was a very valuable lesson for Leverkusen, especially Xabi. They can learn a lot from there to be able to make themselves even better when they face more difficult competition next season, namely in the Champoins League. Their defeat in the Europa League final was surprising, because anyone would definitely make Leverkusen the main favorite. But at the same time they had to suffer defeat and that was 3 goals without reply, something I have rarely or never seen during this season.
In the Champions League everything will be much more difficult than what they experienced in the Europa League. They must be ready for all of this, and they can make preparations as quickly as possible. Xabi must ensure that his team is fully ready to face the next season. He also has to ensure that his team's mental condition is in very good condition, because whether they like it or not, the pressure in the Champions League will be much heavier than what they are feeling now.
Moreover, next season could also be Xabi last season with Leverkusen so they will definitely try their best and really show their best performance in every match.
Even though they failed, it was still very happy thing for everyone because it had been long time since Leverkusen had been in the Europa League final and this season they recorded their name as runners-up in the Europa League.
Previously, Leverkusen was also just team that was always in not very good condition, they spent every season failing and were team that was very easy to beat by other big team.
I sure they will continue to try to learn and improve any existing shortcomings, defeat does not mean destruction and defeat can be the beginning of building an increasingly formidable strength.
Yes, we see how Leverkusen will compete in the UCL, whether they can play as well as in the Europa League or not, but I admit that the competition will be much more difficult than in the Europa League.