I have had problems with both my D7000 and D800 back focusing, the D800 even made a trip back to Nikon for AF repairs. To no avail. I have been putting off doing the AF fine tuning as I thought it too complicated and just defaulted to manual focus mode. I recently viewed some uTube videos and spent the time to figure it all out. Turned out every single one of my AF lenses on both bodes needed some form of adjustment.
I would encourage anyone with a D7000 or D800 to spend time and go thru the AF fine tuning procedure, its not as hard as it seems, and will make a difference.