Posey easily and without a doubt has the potential to hit 20-25 plus home runs a year.
As you and others have shown, you don't have to be a fan of a certain team to mention or talk about a certain player. For anyone who thinks that they have to follow "their team", you don't. I know a ton of people who have only followed teams because they think/feel that they have to for various different reasons.
As for Austin Jackson, he definitely deserves an A potential. I don't care how high his strike out rate is. That means absolutely nothing for a player who has the skill set/ability that he does.