WIS's default settings are horrible. In fact, I recently started a thread called "Why are default settings so horrible?".
This one is particularly baffling, since WIS will usually put the player with more PA in the lineup (in my experience, at least). And Henderson not only has more PA, his $/PA is higher too, so he should clearly be the favorite to start.
By the way, in a league with usable AAA batters, I think a player like DeRosa (okay defensively at 4 positions) is a good player to have around. Let him plug the holes, wherever they may be. (I'm assuming you haven't drafted a full-season's worth of PA at all the positions DeRosa's eligible to play?)