I think it's all a matter of perception. In comparison to Roy, Elan is a moron. In comparison to Thog, he's a genius, and it kinda shows in this strip, though not entirely because showing too much is just wrong.
Well, without Roy to do the thinking, Elan just might have to get his act together if he hopes to save Haley. I, for one, never quite saw him as being stupid.. ...Just prone to acting silly for the fun of it.
Elan seemed intelligent to you guys in that strip? He couldn't keep track of which one he was in describing the plot against him. A bard with poor communication skills seems pretty dim to me...