Due to an excessive runout (side-to-side wobble) of disc plate, the thickness of disc plate is uneven.
WARNING: This page is about a different car, the 2005 Mazda MPV. However, it is still accessible from the selected car via links, so may be relevant.
If the runout is more than 0.05 mm {0.002 in} 10 mm {0.39 in} from the disc plate edge, uneven wear occurs on the disc plate because of uneven pad/plate contact.
If the runout is less than 0.05 mm {0.002 in} , uneven wear does not occur.