Ten Hang might make a better coach for Leverkusen and continue from Xabi stop if the club would give him maximum support needed and players he wants to work with.
I think during his time at Man United he couldn't maximize. I don't know exactly what caused it. But during his time at Man United I think he failed. Even with many players of his choice. So let's wait I will not have big expectations with the champion for Leverkusen. But if I look at history, it seems that Ten Hag is not better than Xabi Alonso in terms of achievement even though it is a different league. But the league conditions are very different so let's see what happens.
Manchester United had so many players when ETH took over as the manager of the team and the management gave him the maximum support needed to lead the team well but the manager couldn't handle the players very well instead he decided to have issues with most of the players to the point that he had to keep some players in the bench just because they do not obey him and that is one of the things that affected his relationship with the players and it affected the performance of the team.
Bayer Leverkusen is a different club and they have good players which he can confirm because Xabi Alonso worked with them to achieve a very good result, I believe ETH will put in his effort to ensure he achieve a better result than Xabi Alonso.