Jack Sock : (3) " My goal is to be competing to win tournaments that I’m playing instead of just content with making a quarter. " - Jack Sock " Used to be some liabilities people would talk about in my game. I feel like I have cleaned those up pretty well. Returning was big for me. I think I’ve gotten a pretty good hold on that. " - Jack Sock " I think clearly I’ve proven I can play at the highest of levels. " - Jack Sock