I've seen the limited footage. Looked to me like Brandon was being more active, but Maidana was picking his spots and landing the cleaner shots. Which is how I suspect a real fight would have gone down, with those clean shots eventually taking a toll on Rios.
Maidana pummels Rios with ease. Both crude fighters but Maidana has actually shown to be more versatile and added dimension to his game over the course of his career, that's including a better jab, angles, and boxing fundamentals. Brandon Rios was a walking embodiment of a one style only fighter. I think a more fair matchup would be Brandon Rios vs Ruslan Provodnikov.
I think Provo would have battered Rios. Provo was stronger, had more power, faster hands, and a better chin.