The BMI guys have been operating out of Heathrow for years, if you were running close on the ILS you always wanted a BMI in front as they were always quick off the runway, polite on the radio and generally good operators.
Given all the above I'm sure they will all enjoy their time in BA, at the coal face the operation isn't any different. No one cares whether or not they would/wouldn't have passed the HR hoop jumping competition, the procurement has given them direct entry. Well done, good luck and welcome.
Due to bringing so many airframes with them the numbers of pilots is, from a recruitment perspective, irrelevant. What has happened is that there is no spare training capacity on the Airbus fleet (LPC/OPC & differences training to be done) and they are holding back SH to LH transfer to maintain some experience on the 'Bus.
Once completed and given the economic enviroment we might see the DEP process pick up again. If/when the recovery comes BA will need the numbers ready.