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I have seen Leverkusen consistently on the winning track and at the top of the standings. In my opinion, their squad is quite better. If they release one of the players from the current main squad or for example buy a new player to fill the main squad, of course there will definitely be a change in style. The game on the field is not as usual, there are many cases of several clubs experiencing changes in the game when they have new players or lose players in the main squad.
You don't have to take advantage of the transfer market in January because I think Leverkusen will consistently succeed in winning the title this season and get rid of Munich who have dominated the Bundesliga for so long, Xabi Alonso will of course fight hard to maintain Leverkusen's consistency until the end of the season.
Xabi Alonso needs to be selective in targeting players in the January transfer market, the need for new energy in the starting XI is not that urgent but as an adequate rotation option they need to do it. The most unpredictable challenge is injury, Laverkursen has a busy match schedule and to compensate for this requires an even squad depth so that it can be stable in each competition. For now, there is no visible weakness in Xabi Alonso squad, as competition increases, this will show itself.
Consistency to achieve success at the end of the season requires many things, Xabi Alonso really understands the dynamics of the Bundesliga and the dominance of Bayern Munich because he was once part of them. The Bundesliga, European League and DFB Pokal are favorites for Laverkusen as a strong candidate to challenge for the title, the scale of competition priorities means that Xabi Alonso needs to do something in the transfer market.