Who would win a clean de Ruyter-Duquesne contest?

Would de Ruyter defeat Duquesne in an otherwise even fleet action?

Probably; de Ruyter generally benefited from more competent subordinate commanders.

A hypothetical even contest favors de Ruyter because he tended to have more competent subordinates. The actual battles gave a less direct comparison: at Stromboli, convoy protection and Dutch logistical limits shaped the fight, while Spanish coalition command distorted the contest at Augusta.