Hewitt had better tennis IQ, mentality, passing shots/lob and a better second serve.
Safin didn't have better volleys than Murray that's for sure. He arguably surpassed Murray in every other aspect except defense and return of serve.
Defense is underrated. Murray would return Safins shots that he'd have no right to return and either gain advantage in the rally and hit a winner or force Safin into error.
Basically---a Berdych-Djokovic type of match. We know who mainly wins those !