Well, break it down. He has 80 speed - stole 88 in '14. He has hit 21 triples the last three seasons. Hit .300 with average .375 OBP at every level. Scouts have said his CF defense is vastly improved/very good. Had 3 HR in 189 AB as a 22 year old.
The only thing I'm projecting that he hasn't done at a lower level is that he'll develop from a 10 HR guy to a 15-20 HR guy. If you use your big muscles/lower body - kind of the opposite of what Heyward does - a smaller man can hit for some power.
I heard an interview with Mallex last year when he was going good in which he addressed this, felt he could develop more power without sacrificing his basic skills, and expressed disgust that anyone would regard him as a "slap hitter" (his words). I was also impressed with his intelligence. I like smart players and think they stand a better chance of improving than dumb, toolsy players.
So I'm bullish on Smith. I'd rather trade Markakis, who could help somebody, and turn over one of the corners to Mallex for the season and see how it goes...either now or in July.