But anyway you are right that Manchester City can give their team a boost by signing Wirtz. Because Manchester City now needs new players. Kevin De Bruney may also could leave the club for next season and Rodri is also injured. So signing new players in winter can give a lot of boost.
We should stop exaggerating players' market values; Wirtz isn't worth anything close to €100 million yet; he only had one good season and a good performance in the EUROs, but he hasn't done much this season to justify that price tag, and Bayer will not let him join another team in the middle of the season; what Pep desperately needs is DM backup for Rodri so they don't have to rely on him too much.
Pep Guardiola really only needs Rodri back in the squad, Florian Wirtz doesn't seem to be a priority in the near future. Admit it or not, Manchester City seem to lose their game spirit when Rodri is absent, and their last five matches prove that the strategy implemented by Pep Guardiola can only work perfectly if Rodri is included in the starting XI. Yes, Florian Wirtz is on the rise at the moment, but I also think his market value is not reaching 100 million. Florian Wirtz is more likely to follow Xabi Alonso if the manager parted ways with Leverkusen next season.