The Congolese midfielder has been working with the Spaniard for the first time this week and says the former Real Betis coach has been keen to make his mark on the team immediately.
Mulumbu says it hasn't always been easy for Mel to get his point across due to his inability to speak English but claims he is having a positive affect on the style of football Albion play.
"This will probably be the hardest week of the season, but that's what you expect when you have a new manager," he told the Birmingham Mail.
"It was quite exciting. He's Spanish so obviously he wants to play good football. He showed us the tactics he wants to put in and we just worked as usual. He wants to change the mentality - go forward, play good football.
"For the first session, we all expect to see how he wants us to use the ball, how he wants us to play. We need to be ready for Everton on Monday."