I'm sure Marrone would have been beaten if he'd been playing on the side of the three, because being out there leaves you more vulnerable to being beaten for pace.
Don't get me wrong, Marrone has interesting characteristics and could well become a useful CB (I quite like a midfielder in the middle of a back three - they play more like a sweeper than a third CB), but I see nothing in his performances so far to allow any real judgements to be made.