Ossoff sucked in $30 million, didn't run on anything, and lost by a bigger margin than he did the first time. Lost by a bigger margin than Hillary Clinton. And I didn't think it was possible to be a worse candidate than her.
From what I'm seeing, Ossoff actually won the exact same share of the vote as he did the first time, if not 0.1% more. I personally think it's a little unfair to blame his campaign management for a race he was slated to lose from the start, and Handel's campaign wasn't exactly low on funds either. The national spotlight ended up hurting his campaign more than it helped, and that was more as a result of the media and the national environment than his campaign.
I'm not trying to say that this was some perfect campaign but I personally wouldn't go as far as to say that his campaign was particularly bad. And he did worse than Hillary because he didn't have the privilege of running against Donald Trump in a district as poorly suited for Trump as GA-06. Yes, Handel didn't distance herself from him, but it's still not the same.