They toss the stuff around, but I'm not sure to what extent, if I remember correctly they actually have a unload thing set aside for skis/boards, and just generally longer items, which they might treat differently?
I wrap my sleeping bag around my skis when I use a thin soft bag, Oh, and carry your boots on, if the airline looses your luggage (which happens a lot) you can ski on the rentals they get you but your boots are unique to you.