Robben played for Mourinho at Chelsea.
"He puts out a winning team, it doesn't matter if it's done with nice football or not," Robben told BBC Sport.
"The philosophy at Bayern is the Coach wants to win games by playing nice football.
"I was working under Mourinho for three years at Chelsea. It was a successful time, he's a big personality and as a Coach of a top team you need to be.
"He knew how to work with big players and put them together and let them work together.
"He certainly knew what he was talking about and had the respect of every single player. But we started to play more in this diamond without wingers, which is not good for me.
"The system changed a bit so I made my decision and left."