On Rijkaard he was mostly in defence in 1988 and mostly in midfield in 1992. But probably the most striking feature was how he moved between the two as per the tactical requirements of and within each game. When they turn over Germany in the group stages, it's clear he's working in midfield. Then late on he is shifted back to defence (or shifts himself - you never know with these Dutchies) to deal with their more direct threat.
@Joga Bonito I don't think those wikilinks for '92 are an accurate description of Holland' formation.
My memory of his role in that tournament is of him influencing the game from one end of the park to the other.