Simplify the following text for a Grade 9 native English-speaking person.
Original: Marcelo Alberto Bielsa Caldera ( nicknamed Loco Bielsa , `` Madman '' Bielsa ) ( born July 21 , 1955 ) is an Argentine association football coach and former defender , born in Rosario , Santa Fe .
Simplified: Marcelo Bielsa ( born 21 July , 1955 ) is a former Argentine football player .