I doubt V Mart ever juiced, though I couldn't say that for sure. Have met him a few times, and though he's got some pop in his bat, he's certainly not built up like some of the other guys you'd expect to be using roids (not that he's a small guy, but he just doesn't look like he spends most his time in the weight room).
The guy is incredibly streaky too, and he hates cold weather. Give him some time. I think by June the ball will be flying off his bat again.