Obstruction -

[Whowefoolin]

If the ball is in left field and the play is at first or home, then ball must be in the in-field to be considered in "the act" of fielding (defining infield I am considering the area to be called as an infield fly).

If ball is in right field and the play is to third or home same as above.

If ball is in outfield and fielder has possession, then any immediate base close to make a play is in the act.

If it is in the infield, then all bases able to make a play would be potentially in the act.

Rule of thumb only.

I learned that here, not at a mandatory meeting.