Those who get grilled on the technical interview are usually the ones who get a FO as their assessor (and that's not uncommon in any LoCo). Young guys tend to know their ATPL subjects far better than many of the experienced lot, most of whom don't really do much reading beyond their Company OMs. They also tend to be far stricter in the sim, requiring exact adherence to procedures, callouts etc and expect a black-and-white answer to everything.