.....
Xabi was the reason why Leverkusen could compete with Bayern for the title. Losing him to Madrid gave no clarity about club's future. So Wirtz and Frimpong follows him. Leverkusen is officially back as a mid table team by losing those guys. Bundesliga seems to be a farmer league again by Bayern.
In my very opinion I think you're being too in a hurry to conclude what the future of Bayer Leverkusen and the bundesliga would be, just because one man as a coach left his team where he was doing excellent with competition in the league and which also includes a few of his players. We didn't know what Xabi could do when he first arrived at Leverkusen until the season went to a length with him, I think same should be extended to Ten Hag having taken over the job. No need for hasty conclusions yet.