I think it inflates defensive numbers if anything. It covers lack of mobility. Man to Man takes athletic ability in spades. It is much easier to defend in the zone. Rebounding is probably lessoned in the zone.
How would playing in a zone inflate defensive numbers? Zones tend to equate with worst rebounding. Hence, defensive numbers would be deflated rather than inflated.
Because Melo played in a zone full-time, it's hard to read how good of a post or screen defender he'll be. Also how foul prone. But something that impressed me, which surprised me given the general negative vibe around him and his all around awful freshman year, is how engaged he was. The impression I got from watching him keep his feet active, his hands up and head on a swivel is that he really cared about being the "QB" of Syracuse's defense. He seemed to have the on-court smarts to do it too.
About his passing again, it's really underrated. He's not Brad Miller, dishing out backcut assists but just like he was alert on defense, he had no problems seeing the floor on offense. Just being able to participate in a team's ball movement puts him ahead of a lot of other centers. I think his basketball IQ is above average. If that's the case, at 7 feet and good shotblocking ability, he has the chance to be a solid contributor.