I agree with you that Bayern Leverkusen will be stronger next season. Bayern Leverkusen's performance this season is not luck; if not, they wouldn't have displayed the same performance in the Europa League competition. Xabi Alonso knows the tactics he has deployed at Bayern Leverkusen that have made them successful this season in all competitions. Bayern Leverkusen has made their fans happy by winning this season's Bundesliga title. They are waiting to play the DFB Pokal Cup finals and the Europa League finals, and they are unbeaten in 50 matches played this season.
How sure are you that they can win the trophy next season again when they are about selling some of their good players, bids have already started coming in and if they sell some specific players, their performance will reduce drastically and they’ll have to struggle back into the league and other competitions they’ll be participating in. They should know how to keep those players that are important to them to be in their best and if they can’t keep them, a replacement should found for them before the transfer window closes at the beginning of the season. Bayern Leverkusen are rated amongst the best team in Europe and it’s because of their performance this season, if they can keep it up, they’ll keep going higher, so I hope they do the right thing to keep them above other teams in the competition.