i checked just now the genie scout of some players and was wondering players like gabriel silva the left back has got pa of like 146 and that and many players with decent stats have got low pa so yh
PA is the Potential Ability of a player, CA is the current ability. In order for the player to reach their PA, they need good determination, ambition and professionalism. It also helps if the club have good coaches and training facilities.
you have to look at the current/potential ability rating as well. i.e. a player with current ability 140 but ca rating of 72% is better than a player with ca 170, ca rating of 68%.