Because his hand has a shorter distance to travel because the guy whose foot is on the inside has to cross his own lead leg(w his r hand) to land his punch. The guy with his leg on the outside doesn't have to cross anything he can shoot his punch straight down the middle.
still the problem with this is the guy with his foot wrong can also punch down the middle. it isnt true that he cant.
heres tracy patterson throwing a right hand down the middle at eddie hopson. hopson is circling to his right with a check hook over pattersons jab. according to your theory hopson is at an advantage and patterson cant be more wrong with where his foot is supposed to be here.
hopsons foot is way outside of pattersons foot and pattersons foot cant be any more wrong yet that right hand he threw cant be any more down the middle. the claim that you cant throw down the middle with your foot "wrong" just isnt true.
Where would he have to throw the right hand to land it? ^^ that's an awkward punch to and Rigo has the benefit in this situation.
the position rigondeaux gets in here wasnt because of his foot. it was because of his slipping motion. heres a different angle of the same punch where you can see the way his head slips over to the side.
where your foot is wouldnt allow your body to lean over to one side or the other. you would have to preform a slipping motion to do that, your foot isnt going to automatically do that for you. that is something either of them could do, despite the fact that riondeauxs foot was right, and marroquins foot was wrong.
to prove that, heres a screenshot of where they were before the exchange started.
each of them are in a position to throw down the middle from each of their foot positions. what carried rigondeaux over to the side was his slipping motion, which had nothing to do with where his foot was, and everything to do with performing a slipping motion the right way.
Look at the Floyd Manny gif you posted if Manny's body wasn't leaning to his left Floyd would not have been able to land it that way he would have to throw that punch across his lead leg that is an awkward punch to throw.
so is it because of foot position or is it because of how your upper body is leaning? if you are you saying for manny to be in good position, his foot has to be at a special location plus he also has to be leaning over to his right, then you have just invalidated your own theory. because you can lean over with or without the foot being at a special location by just performing the appropriate slipping motion. the theory is therefore either wrong, or it has to be updated somehow to include for this.