How appalling. You come into work when you could be on strike and instead of at least supporting you by managing customer expectations in advance (remember no duty free, cold meals and restricted bar in Traveller during previous IA), BA throw you in at the deep end! Customers may not know why service is so slow, which just generates complaints, stress and not a great working environment. All so easily avoided.
I don't know if they still have the performance dashboard or whatever it's called which rates Crew based on customer (and possibly sccm / peer) feedback but I'd hope too few crew is factored in. If people miss out on a bonus or promotion because of complaints in this kind of situation then that would just be the icing on the cake!