GSP may not necessarily be a good indicator of how one would do in a tournament setting, but we are long past the days where anybody could get and stay in Elite. To raise GSP, you have to consistently outplay your opponents. It doesn't matter what rules or modes you play, you're not climbing and staying at the top unless you practice and up your game, however you decide to play it. Whatever worth you assign to it is purely up to you, but there's no denying it is effective at matching up and placing players based on overall skill (just so long as you understand the middle areas are more volatile in numbers than the ends. The gap between 4,500,000 and 4,700,000 is just as big if not bigger than 2,000,000 to 3,000,000).