"He has been a big change for the club," the France international told the Daily Express.
"We never used to work with a lot of tactics before. This is something Andre has brought to the club - a lot of tactics and also a lot of discipline. That is something we needed years before.
"It was not easy for Andre to come in because we had a good season last year. But we didn't qualify for the Champions League and that was our main target.
"He came with some very good ideas in July and is working to win football matches - simple as that.
"His main thing is to have discipline in the game and have everybody doing their job. From that, we can win matches.
"We have to work a lot tactically during the week and that is what we have been doing since July.
"We know what we need to do. He brings something different to us, makes us concentrate more. He likes to be even more focused.
"He gives us the best chance to succeed with his training and his talking and he is very close to us. We exchange a lot with him, which is very important for the team."