He proved he could be successful. Just shows again how stubborn perceptions get exposed by reality.
Through the various levels of pro-am ball I've participated in over the decades -- playing, coaching, watching -- this question, paraphrased here, always comes up:
Is he good or just doing good (well...)?
All-Star rosters at amateur levels used to be determined by merit, with voters selecting worthy players based on their seasons, often with statistics as credentials. Nowadays, I see Little Leaguers have to try out for All-Star squads, in front of evaluators who don't know the kids or haven't ever seen them play in actual games. So naturally, anyone with a good arm and decent wheels makes the team (even if he's 0-for-20 with 20 strikeouts).
Does he look good or is he actually performing? Now someone will say, 29 other teams ignored Wacha before he signed with the Pads. Yup, he proved them all wrong.