Apparently it is physiologically quicker for hands/arms to be able to move upwards and outwards reflexively then it is to move them downwards/inwards.  This is part of the reason that, on defence, it is more beneficial to keep you hands low and close to your body as a starting position.

That said, if the person you're marking keeps throwing overheads or high-releases then stick a hand up in front of their face, generally the hand on the break side. Be ready to bring it down again quickly to preevent a break-force throw once you start to move around though.