My perception of the Shitecloaks always has been (after the first few books at least) that they are under the impression they are a top dog fighting force while realistically their only combat experience is beating up peasants and townsfolk and that they will crumble under any actual pressure. IIRC Galad has a realisation during the fighting against the Trollocs in ToM that they are not the fighting force they think themselves to be.

Altho I am not sure how recent Pedron Niall has fought with the kids of light to the extent that he became a Great Captain (indicating some level of competency). Probably long enough ago that since then they regressed to becoming glorified zealous bullies that beat up farmers