Hard base mousepads fix carpet sinking.

Yes, a hard or rigid base is the way to go.

Carpet is basically a sponge for pressure. Soft rubber or foam bases will compress into the fibers, leaving you with a wobbly, uneven surface that drives your aim crazy. A hard plastic or aluminum base distributes your weight across the whole pad so it stays flat.

If your carpet is plush or thick, go with a thicker rigid pad (the kind with a stiff rubber core, not just a thin sheet). The cheap cloth pads with a foam bottom will sink no matter what. You can also just use a solid desk mat or a hard surface mousepad on top of a thin board.

Your mouse will thank you for not having to fight the carpet.