I don't expect him to fail in Leverkusen because he should be able to manage the team since less pressure is on him compared to when he is in United. The only thing that can be his problem is buying good players to replace the ones that have left the club. That might be a big challenge to him, but I believe that we will see positive results from Leverkusen next season.
You're right, Eric Ten Hag should not fail in his new club as a manager afterall the club is a bit organized compared to his former club where he was unable to turn things around before he was sacked, the thing is we know this coach, he doesn't listen, he does things they way he want it and I hope he gets it right this time, he should be able to take up that duty very well, all eyes on him, if he fail in this club, then there's a problem, I believe the club will want to get him some place that will suit what he wants but where the problem will be, is utilizing those players very well, the truth despite that we don't expect him to fail, personally I don't trust Eric Ten Hag coaching pattern but lets see what he got for his new side next season.