Simplify the following text for a Grade 8 native English-speaking person.
Original: MÃ rcio Roberto dos Santos , best known as MÃ rcio Santos ( born September 15 , 1969 ) is a former Brazilian footballer , who played as a defender for such teams as Internacional , Fiorentina and Ajax .
Simplified: MÃ rcio Roberto dos Santos ( born 15 September , 1969 ) is a former Brazilian football player .