You wana get outa the way while doing damage, setting up your win. So..
Up your Elbows! it will make contact the fists and probably damage/null them, while you move with a paceful retreating side step to any sides, as your elbows make contact with oncoming fists. Try to get this technique, its the simplest, and battle tested. (Destroyed many new JKDers trying to use it on me

)
How come nonya guys above got a good suggestion? Its true if the SB is already executed and done its job, its over. But w're talking about moment you know its coming, or will come (as this guy youre sparring uses it lot) and need to defend/counter it.
Throw in the towel? then what? the fight continues? or you guys trap each other around and repeat dancing? No!
Train with Aim!
E.D.
SORRY. This got posted here by mistake. was supposed to be posted as a reply in the "Defense Against The Straight Blast" post.