Obviously the competition in the German Bundesliga is not as tough as the one he get to face in the premier league, sometimes amongst my peers we do argue it that any coach who survives the premier league with a very awesome performance is most likely indeed a very good coach and can do pretty well in any other leagues, I believe it is no news the Premier League is the best in the world and so we should not expect any less, the pressure in the Bundesliga is far less as compared to what he had to put up with in the premier league so I expect only the best from him in the Bundesliga.
However, we cannot underestimate the Bundesliga, because it is still one of the most competitive leagues in Europe, even though it is not as intense as the Premier League in terms of pressure and team competition, but coaches, especially those who have popularity and experience coaching big clubs, their reputations are at stake if they fail to provide the best performance to the teams they coach.
and also keep in mind that every league has its own challenges, the Bundesliga has a different style of play, a more stable club structure, even though the competition is not as fierce as the Premier League, but it is one of the best leagues, so it cannot be underestimated.