However, De Bruyne was instrumental as Manchester City broke multiple Premier League records en route to the title, which included breaking the 100-point barrier, as well as winning the EFL Cup.
"I was surprised De Bruyne didn't beat Salah to the Player of the Year," Martinez told The Mirror.
"Mo has had an incredible season, the best season in his career. But Kevin almost came into a new way of working with Pep Guardiola, who has a really strong connection with him, and he influenced a lot of things.
"This is a team that has broken all the records in the Premier League. Individual awards are given for individual performances, but those individual performances come as part of a team in what is a team sport and Kevin, in the early part of the season, was magnificent.
"I understand what Mo did, but, out of the two, Kevin probably had a bigger effect over the season."
De Bruyne is expected to be one of the first names considered by Martinez when naming Belgium's 23-man squad for this summer's World Cup finals in Russia.