Greenmonsters
Wannabe Duck Boat Owner
NoVA - As suggested by Brett and Ajay (2 experienced and respected DFP-contributing umpires BTW), you are making this far more complicated than it should be! In your hypothetical with the catcher the same criteria hold, its not interference if the firstbaseman isn't prevented from making the catch and the batter/runner isn't hit by the thrown ball outside of the running lane.