It will take time for Ten Hag to make changes at Leverkusen because after all the departure of Xabi Alonso has made this team have to go through adjustments. The target next season to compete for the title but it will be difficult to achieve if Leverkusen does not strengthen the team with the swelling of several important players. Everyone associates Ten Hag's failure at Manchester United and maybe many people are pessimistic that Leverkusen under Ten Hag's coaching can be much more successful. Anything can happen but we need to give him time and trust him because who knows he could repeat the success he had at Ajax.
The club has lost so many players already and I am sure some will still go before the transfer window closes and losing Alonso also will definitely affect the team and things will be more difficult for the new coach. I also think things won't happen instantly when Ten Hag takes over it will take a little time and so i don't expect them to be in the title race this coming season but if they should be in it then I would be surprised and commend Ten Hag for a job Weldon.
Being in Leverkusen will have less pressure than at Manchester United and I think they will also give him time and trust his process. I have a feeling that he might do well in Leverkusen and redeem himself.
But everyone is not getting it right about him now, he may be so poor at Manchester United but it doesn’t mean same will happen in this new club he’d joined now to manage especially when there is high hopes on him to keep the team on high hopes of reviving their good form.
You're right, he used to be a very good coach but coming to Manchester United change how everyone viewed him which I believe is the pressure at the club, the desperation of success is what is killing the team and affecting the coaches there which I believe it won't be so at Leverkusen despite tasting glory recently. I have believe that things will be different for Ten Hag now and he might do at his new club.