Why was Zico played so little after first 2 matches in the 1978 world cup?

Arthur Antunes Coimbra, arguably the greatest brazilian footballer since Pele,was played for just few minutes each in brazil's matches against Austria, Peru, Argentina and Poland in '78 world cup.even considering brazil had (maybe) abundance of talent in the squad...it seems bit of a dodgy decision by them as Zico was already.a world class players as he had proven in quite a few matches in brazil colours.those games are available in the web where he showcased his special talent.were it...

Why was Zico played so little after first 2 matches in the 1978 world cup?