And although Antonio Conte was happy to see him leave the Blues, Martinez reckons Batshuayi is capable at playing for a big club in England.
"To play at a World Cup is a unique moment in your career, so you have to be able to play and perform at club level in order to be in that squad," said Martinez.
"For Michy Batshuayi, it's not about staying in the Premier League, it's about finding a club where you can have a big role and you can feel you have an influence in the team.
"Michy was always ready at Chelsea, but the competition was really strong in that number nine role.
"He has gone to Borussia Dortmund and as a striker you need to score that first goal as quickly as you can, he scored two in his debut.
"You can see he is happy, free and sometimes a move in the winter window gives you that.
"For Michy, it's given him a very strong opportunity to be in the World Cup squad because of the environment he's found."