funny you should ask, a buddy just got one of my right handed balls, he's left handed, dropped from 15 to 14# and decided not to use his thumb , he's bowled 2 teens, 2 220's, 2 240's, and a 275 ( 11 strikes and an open ). he's tried different fingers in holes (no jokes please) and has twice as many revs. he used to average 215 but wanted more, he might've found something. if it works, roll with it.