this si what makes the game more of an art than science sometimes. You can't "compare" the numbers so to speak, you have to ave a feel for where the draft is going and what is likely to happen.
I'd say picking a guy to trade later is sometimes rough. Although in this case, take helton. If he bounces back, then you have all sorts of flexibility. If he goes 25, .300 85, then you have a nice player who could serve you well in a trade.
Although with certain things like steals and saves, taking too many of them just devalues your assets, since if one team hogs them all, the other teams can get more points for less investment than usual. If they all refuse to trade with you, you can jsut get stuck.