yep and gets back in orthodox so quickly, most miss it unless they know what to look for GGG does this very well; my guess is that he's naturally left-handed (eg, holds a pen, throws, and eats with his left hand), but they turned him around when he started training. That would also explain the fact that he's KO'ed fighters with either hand still i think maybe the OP has something else in mind, given he mentioned Pirog's KO of Jacobs. What you mentioned--and i think you are spot on--is shifting, which to me is done with defensive (recovery) intention
Nonito Donaire back in the day. Would come off the stool and fight left-handed for a whole round before coming out for the next round back to orthodox.