I found this in the sharkscope site it says, The Ability rating is a rating that goes up to 100 and shows a player's ability based on an assessment of all the other statistics we have compiled for that player. It allows you to easily compare players who play significantly different stake levels and tournament types - for example a player who loses a small amount at high stakes games is likely a better player than a player that wins money at very low stakes games - and so may well have a higher Ability rating.
