Win % can be misleading.
Arteta was 47% at Arsenal last season. At a similar age, Klopp got 35% at Mainz which got him the Dortmund job.
It is relative to the team being managed, the league they are in and the overall capability of the squad.
Brighton have had 41 points for the last two seasons and been comfortable from relegation while playing good Football. Many made them favourites for relegation in both of those seasons, because of the squad abilities.
Potter is a good manager, his win % won't stop him getting a good opportunity with a more ambitious club.