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.
Still been disappointed at Leverkusen at this time may mean you had a very huge expectation from them and you probably esteemed the preseason game to a good extent but then it is possible same is not what Leverkusen was about or that particular game, Leverkusen may ha e seen that game as just training and helping their opponent gain confidence when they go back to play at their level. It may surprise you to know that some of the Leverkusen players may even be at their best and will be really in their best form waiting for the season to commence and have just used that game to warm up.