Fake Tag or Spastic?

[TussAgee11]

R1, outs dont matter. Groundball to 2nd baseman who comes in front of the oncoming runner. The ball goes through the wickets, then the player reaches back and tries to tag the runner. I was PU, BU didn't call anything. I thought it could either be a fake tag or obstruction (the glove hit the runner and possibly impeded him). Obviously obs would have only awarded R1 2nd, but fake tag would have had worse consequences. It appeared as though F4 tried to do everything to fast, and probably was aware the ball wasn't in his glove, but his motion towards the runner had already started.

So, fake tag, or spaz F4?