Players are sold when the right time comes and their value is high, and that’s exactly what Bayer Leverkusen did.
At Manchester United, I think he was given enough time, yet he achieved nothing. The Leverkusen board most likely thought he wouldn’t be able to do anything here either, which is why they sacked him.
In the Eredivisie, there are basically only two big clubs: Ajax and PSV.
It’s completely natural for one of these two to win the league and dominate it.
While it is true that Leverkusen should have sold those players in order to profit the peak and that way they could get a lot better future ahead of them with money at hand. The mistake wasn't selling, it was buying. They have overpaid on many players this year and that caused them to not have the result they wish to have. If they end up with bad transfers, then they are not going to be a team that can do fine, hence the problem we are seeing right now.
This issue will not be simple and we are not going to see them have the result they wish to have. If they really want to do better, then they should use the money to got from those transfers into something that would make more sense. Check out the list of players that they got, and how much they paid for them.
https://www.transfermarkt.com.tr/bayer-04-leverkusen/transfers/verein/15/saison_id/2025After all of that sale, they are only in 30 million profit. When is the next time you think Leverkusen could make 230 million from selling players in a single summer? I am 100% sure that it is not going to happen anytime soon, and yet they have wasted all of that money, for getting bunch of mediocre players who will not turn out to be 100 million euro players. They spent this summer very wrong.