Inattentive Runner - Collision

[Sven K]

First post but I have been lurking and learning for a while...

Runners on first and second with one out. Batter hits a three hopper to the third basemen who fields it right in the base line. The runner is on his way to third (oblivious of the play developing in front of him) and as the fielder is rising up to make the tag the runner plows into him. Both fall to the ground in a heap. The question: is the batter out since the fielder was denied his bona fide chance to throw out the runner and complete the double play? It seems to me that this is a judgement thing but I have to admit that I don't know the rule. You see it called occasionally on the typical 6-4-3 double play.

It seemed like bad form to ask the crew about this immediately after since the runner was injured and bleeding and still laying on the ground. When asked later the upires informed me that it can't be assumed that the double play would have been completed and only the obtuse runner is called out. Is this correct? If so it doesn't seem fair.