I also disappointed with Bayer Leverkusen 5-1 loss to Flamengo U20 team. It was worrying sign because Leverkusen had very little of ball made few good passes and barely shot at goal. Flamengo U20 team clearly controlled game which led to their five goals. Yes that is right that many Leverkusen players need to improve much and are making too many mistakes meaning they have some big problems to fix before main season begins.
Yep, I thought Leverkusen use their Academy players, but when I check their lineup in that match, most of them are senior players
https://www.besoccer.com/match/flamengo-u20-juvenil/bayer-leverkusen/202612247/lineupsI think there's no excuse, even though Leverkusen lost Tah, Frimpong and Wirtz, but the current players should able to beat mediocre team. Unfortunately they lost with big margin, this show if Ten Hag was the problem.