I don't have huge experience of flying with thousands of different FOs but, 99% of the better pilots were ex military. Not to say the civvy trained guy couldn't been just as capable with the same training. The civvy guys do the day to day job satisfactorily but it's in the sim and during emergencies that the differences show up. Their capacity is reached far quicker than their military counterparts. It's when capacity is reached that basic handling can go out of the window