Leverkusen will likely struggle this season with the way that they are going selling their players to other teams they are actually making a big mistake which will affect the team performance this coming season because Leverkusen will be playing in the champions League so they really needs to replace these players that are leaving with the monies that they have made from the sale of players.
They have not done so much in this transfer window at this time and they actually need to make some moves to keep the team in a very good form but maybe ten Hag wants to work with that which he has already as a team so that is why he may not have been to bothered with getting some more new players. Even the champions league they may not be playing to win the trophy this season because they look like they do not have the capacity to win that so they will just get as much experience as possible and try to go beyond the first stage of the league.