If you're curious as to why, I'm mentally comparing Brand with Randolph. Randolph came out after his freshman year but he was still pretty raw. He's just now really turning in great performances.
I think it's about right to expect Chandler or Curry to click by the beginning of next year. If they don't click by then (barring another coaching change to set them back) I know personally I will really start to wonder.
Chandler might have actually been clicking at the beginning of this season, but that back is a major issue... it has to be priority #1 for him to get his back into order.
Curry... not clicking yet. But getting there, slowly.