I am not fighting the reasons for his sack neither am I disregarding the obvious but clearly we can agree he was not given time enough, he did not play upto five Bundesliga games, I also agree that they do not have to wait till they are relegated before they take decisions on sacking him or not but then it still does not change the fact that somehow this was unfair to him as even his reputation may be affected by this, he was not a great coach at Manchester does not mean he can not elsewhere, he just needed some little more time, after all there are coaches who starts off poorly and eventually finished decently.
Ten Hag’s dismissal was the right decision, not only because of Leverkusen’s declining performances but also due to several deeper issues, such as his interference in player transfers, friction with the staff, and other actions that displeased management. initially, Leverkusen appointed him with the expectation that he would focus strictly on coaching and keep the club’s business matters separate, however, over time, he became increasingly involved in areas outside his role, which ultimately led to his dismissal. he is the one who made the situation worse for himself.
I think ultimately a coach should have a say in player transfers, but in this particular case literally everyone knew beforehand how many clubs were after some of the most important Leverkusen players and I am sure ten Hag was not hired based on false promises. They probably told him that there will be several players leaving the club. It is normal for every coach to express their discontent about good players going away, but he was aware this could be happening. What did he think? That Leverkusen can turn down these big offers and keep the players instead? He can't complain about something that everyone saw coming anyway.
Apart from that I think Leverkusen immediately came under pressure not only due to the results of those games, but due to how they played. Yes it needs time to build a team, but let's assume that the sporting director of Leverkusen was concerned about how ten Hag set everything up, how he communicated and how he conducted his training sessions, what should Rolfes have done before this long Bundesliga break? I don't know, but if he didn't act and they had lost the next two games after that break, he would have been at serious risk himself (which I think he should be anyways).