I seem to remember reading somewhere that the relatively high survival rate of BofB pilots was down to their inexperience and low hours on type.
On their first or second sorties with fear coursing through their veins any call to say that there was a 'bandit' on their tail caused them to look round over their shoulder trying to see the attacking aircraft. Sub consciously they were also pulling back on the stick while they did this (I know this happens 'cos I have to stop myself from doing it when flying). The result was, with high performance aircraft like the Hurricane and Spitfire, an instant stall and spin taking them out of the line of fire. The pilot then bales out (hopefully) and lands back on British soil thence to fight another day (and with a whole heap of combat experience under his belt).