Fielder interferrence

Question
In the Mets-Cards 6th game, a runner advanced to 2nd on a steel, the throw was high and into center field.  The runner dove into, and was on the bag. The 2nd baseman lay down right on top of him to prevent him from advancing. Why is this not interference?  Did any one else see this? What did I miss?

Answer
Hi Ken:

Thanks for your question; it figures the one game of the NLCS that I missed would result in a rules question!

This is not interference because it is actually called obstruction.  The second baseman is obstructing the runner from advancing.  I have to assume that, in the umpire's opinion, the runner made no attempt to advance to third, and that if that runner had made that attempt, he would not have reached third base successfully (ie: without being tagged out).  Therefore, no award is made.

I hope this answers your question :).

Thanks,
Gareth