Obstruction Question

[MountieSB]

I'm a coach, not an umpire - please continue reading anyway!

R1 on first base, one out, B1 hits a high chopper to F4, F4 fields ball (has ball in glove) and R1 collides with F4 in the baseline. BU calls obstruction, R1 out for obstructing F4. Because F4 was run over, she was unable to complete a throw to first base to get that out (and turn a double play).

My question is this - Is this obstruction, or merely a collision that resulted in an out because of a tag (like you would get with a collision on a play at the plate)? Either way, R1 is out, but I'm just looking for clarification. Because we got an out (I was DC), I was obviously happy, but the other coaches and I were talking about it after the end of the game wondering if it was obstruction or just a tag out. Thoughts?

Thanks for your time.

Mike