I don't even know where the 6'11 came from. The media guide I have from the summer league lists him at 6'9- 210 and that is what I thought he was. I often wondered why everyone kept saying he could be the starting center?

I found this from Wikipedia:
Johnson is a power forward who was selected by the Detroit Pistons with the 56th pick of the 2005 NBA Draft. He is listed at 6'9" (2.06m) and 210 lb (95 kg) but has reportedly grown to 6'11" (2.11m)[1] since being drafted.

That footnote indicates it was taken a Piston article written by Keith Langlois, but there is no date on it.

Agree that in the x-mas video, AJ's shoulders look about an inch and half shorter than Sheeds