Outliers are generally a poor place to evaluate balance from. You're not going to nerf the best tank player in the world by simply boosting a job's potency values (they'll just swap), and it's irrelevant to the rest of the playerbase. The truth is that this is probably the tightest tank balance that we've seen in the past ten years of this game. You can try and cherry pick values to try and wrangle out an advantage for your preferred job amongst players who don't understand how such statistics work, but you're much better off investing that time in practicing to become better than you are campaigning here for buffs. With the existing balance, player skill is the greatest buff.