To continue the Opta mini-theme, here is a video that explains how they compile their match statistics and how they are preparing for the World Cup this summer. (I tried to embed it into this post, but it wouldn't work for me.)
One thing that struck me when viewing that video was how labor-intensive the task is. Four months of training before being allowed to track a single match…wow. Real-time match tracking through video analysis is still in its infancy, but it would have its advantages over human tracking.
Opta has done an impressive job with collecting all those sweet sweet match data, but I don't think all of the gold in those data have been mined yet.