I just played against my housemate who used to be a junior-national level player, he did the same just replying 100% of my returns but not slamming them. I ask

I just played against my housemate who used to be a junior-national level player, he did the same just replying 100% of my returns but not slamming them. I asked him to play 100% and he won every point first return or serve.