Possible obstruction call at first, I may have blown it

[MoJo]

IMHO.... any time a fielder (who does not have possession of the ball) either impedes or causes a runner to alter her path to the base, it is obstruction

That is How the game is played. There is more than one rule that governs these situations. Calling it different or without penalty would be incorrect .

 

[EdLovrich]

After reading the NSA rule as you wrote it, and comparing to the NFHS rule, it sounds like NSA is trying to include "In the act of catching a thrown ball", which NFHS does make an exception for. NFHS you either have possession of a thrown ball or you cannot be in the base path of the runner. No interpretation by the umpire of 'is the fielder in the act of catching the ball'

Without looking up casebook rulings for NSA, I would GUESS that the fielder in this case is NOT in the act of catching a thrown ball (she had that opportunity already) and has obstructed the runner