Sure you can put them right on the racks, but Chicken can really drip a lot all over the place. I would at least put a pan on the rack below to catch the fat, and make it easier to clean up after.
Bear how come you used pans? Can one just put the thighs directly on the grates?
Just make sure you don't block the flow of heat by crowding a rack with pans or foil.
Here's one I did with the Thighs right on the rack.
Chicken Thighs (Hickory Smoked)
Bear