After the joining of Xabi Alonso changes happen, and then we have good consistency and improvement in quality which are now giving them all success which is surely amazing and players chemistry is also impressive which is having good results in every game without any pressure this is clearly giving indicator how strong and energetic is Xabi Alonso as leader but now can they keep this momentum it's more important because we have mostly teams slips near the end of the season and have problems which hurt them badly.
They are already had good finances so with this all if they are able to keep few players for the long time then surely we can expect results like these for the long otherwise we have few clubs in past they have good success, but suddenly they are also failures due to bad leadership and other bad decisions.
I think building a team that plays like a well oiled machine is the most important thing a manager could do. It is not always about having the best tactic, it is also about building a system that fits all the players and they all know what they are doing.
Like for example, if you remove the left winger at Leverkusen and put Mbappe there, it is not a must that they may get better, I mean they may, but there is a small chance that they may not get better as well. That means, if they wouldn't then it could show how the yare working well together, and everyone knows what they should do, that's chemistry and that's something a manager should be able to do. You need to make sure the whole team is working perfectly together as a manager.