Getting Mayo or Courtney Lee would definitely not be the difference between winning and losing a championship for us. With Mayo, the hope was always to "fix him" and make him better than he's been the past 2 years. But thats far from a sure thing.
And I'm REALLY, REALLY, hesitant to throw max money at a guy like Harden. He's shown nothing, besides being really efficient, to show that he's deserving of max contract money. He can't carry a team as a #1 or even a #2 option, he can't defend at all. He would be a work project for us just like Mayo.