BerniceC: right - what Fencer said. because Your rating is well higher than SandyH's, the system (quite logically) regards Her drawing a game with You as something of an accomplishment on Her part (and thus something worthy of reward) and conversely it sees Your drawing a game with Her as - shall we say - an incidence of Your not playing up to Your potential (and thus something worthy of demerit). She's rewarded with some points; You're demerited some. and there it is.