Watch the master of it; Kostya.
He measured with his left out like an ariel would wait for a shot to come and then his right would follow it back home as he moved in on them.
i thik thats best,following their own left jab back home so that the shot is hidden from their own view and it raises up over their shoulder like a meteor comming over the horizon.
Stepping left wont help in that circumstance though.
theres other ways by opening up your stance going square as you move and then correcting your left leg and landing it.
Best to visualize different senarios and imagine where they are moving to and when you can launch one unseen over their arm,works well timing someone whos in the opposite stance to you.
If they are moving to their right you could step out left and follow them but like you say it turns into a sort of overhand cross,still worksthe same but theres never just only one time for one thing to work.
Wont work all the time but if he overcommitts or over extends in reaction to one of your moves: Imagine switching your feet by taking your left foot around the back of your right foot to avoid his reaching left striaght shot,let it go over your left shoulder and stepping out with your right foot as his left arm returns so you have switched stance around his left arm, now you got momentum behind your end positioning and its unseen comming over the outside of his shoulder and you have moved to the outside of his outer arm,youre safe there ,he isnt.
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