San Diego: Tech Foul in Finals

[Squillo]

I saw the last (second) finals match in the SD regional. The blue alliance won that match, and hence the regional (having already won F-1), because the red alliance got a tech foul that was announced as something like "human player deflecting opponent's ball with their ball". Could someone please explain? I thought a deflection was not a possession, so the human player didn't possess the opponent's ball. I didn't see what happened, so I can't judge it for myself.

Which rule was violated? Anyone know anything more about this 'game changing' foul?

If this happened the way I imagine, then it is clear that when a HP sees an opponent's ball headed for them, they'd better do anything possible to avoid touching it (with a hand or their own ball). But not step out of the box. Seems that could be difficult, but I intend to warn our HPs!