D7000 AF question

I have a D7000 and a 80-200 AF-D. I was taking photos of my 5- year old playing soccer.

I did OK with the autofocusing and getting shots in focus, but I can do better. Any suggestions with settings or what to do? Soccer is tough since there are lots of people on the field, lots of coaches, and lots of other things (i.e. other players, goal posts) that seem to trick my AF.

Has anyone had luck with the 3D auto tracking of the D7000 to lock in on one person when there are other people also in the camera view?

Even if one possible answer is "get the new 70-200 since it has better AF speed", that isnt the right answer for me since the 80-200 is all I can afford.