Xabi Alonso will have to maintain last season's performance if he wants to still be held in high regard in Bayer Leverkusen. Club management don't really give a damn about your past performance because they want current results. It will be difficult for Leverkusen to replicate the unbeaten run next season but they should at least make a mark in the UCL League next season.
Leverkusen's performance has been phenomenal this season. They don't have a squad with star players but they managed to get an unbeaten record in the domestic league and almost became the first team in history to win the invisible treble. And it will be very difficult to repeat the same results next season. Leverkusen's defeat to Atalanta in the UEL final has exposed the weaknesses of Leverkusen's current game. To be honest, Alonso's tactics are really great but it seems like the players can't implement them fully. Correct me if I'm wrong. At that time Leverkusen often used tactics by placing many players on one side so that the opponent was really under pressure. But then Atalanta used high press man-to-man marking which made Leverkusen lose in the UEL final.
Gian Piero Gasperini knows that Leverkusen does not have strong players one on one so this exposes Leverkusen's weaknesses. I think if Alonso manages to improve this aspect next season then Leverkusen might be able to shock Europe once again.
One good thing about Leverkusen is about the good performance they have in this team. In fact, Leverkusen was not in the situation to beat teams like Bayern Munich and even win the Bundesliga title and if I am not mistaken, Leverkusen won the Bundesliga title for the second time in their history which is a great step forward for them.
Leverkusen didn't even spend too much money like Bayern Munich but they mostly won the game because of the amazing teamwork they have in their team thanks to their coach.