It was Leverkusen that ended Bayern long line of winning Bundesliga title every season. For this season, the title remains with Bayern Munich, Leverkusen are still figuring ways of returning to the competition, they are not prepared for the season which we can see from their performance this few games. Well, important players were sold and new coach was brought in, i know the team shouldn't be expecting much right away, if they make top four that is a best recovery achievement to end the season.
Leverkusen do not seem like they are good to get even a good attempt the Bundesliga title. The transfer donee by Leverkusen were not such that will even cause a threat in the Bundesliga, looking at what has happened so far the chances looks very high that Bayern Munich is winning the Bundesliga title a again this season only that we try not to be in a hurry to mention it already.
It seems that Ten Hag will turn Leverkusen into an average club just like what he did to Manchester United, after Xabi Alonso have liberated them from that level. Ten Hag does not know the quality of players to buy that will push a team forward and he doesn't have the skills to improve these average players in order to bring out their best performance.