It's certainly reasonable to hold back on Ten Hag's expectations in his first season with Leverkusen, especially since the team isn't particularly equipped with top players. I don't think we should expect too much next season unless Leverkusen can pull off more unexpected surprises. I also won't judge Ten Hag negatively for those preseason games, as the true assessment will have to be seen in the more serious matches that will come next season. That will be more appropriate to conclude after Ten Hag's first season with Leverkusen.
So, what can we expect from Eric Ten Hag? He hopes he can return to the pinnacle of his coaching career and achieve the same success he achieved during his time with Ajax Amsterdam. This isn't just his first season coaching Leverkusen, but it's also his first coaching a Bundesliga club. He does have considerable coaching experience, but he lacks the experience to coach a Bundesliga club. And if, with ETH, Bayer Leverkusen can't maintain its status as a title contender, then hiring ETH as Leverkusen's new coach would be a poor decision by the club's owners. It's still too early to judge ETH, but the signs of Leverkusen's decline under ETH are already evident.
At the moment the club has lost some really good players, talking about players who were crucial to the club’s success in the last two seasons and to cap it all losing their manager too so I can say that Leverkusen are experiencing a recovery phase and so I won’t be expecting so much from Ten Hag and the team next season because this season will he will be experimenting. Probably from the upper season before the expectations and big objectives can come in.