A Word About "BigLaw"

I recall reading some comments over at Even Schaeffer's Legal Underground where a former BigLaw associate huffed that businesses would do better to hire BigLaw to defend their cases instead of hiring (mere) insurance defense firms, purportedly because BigLaw would be more competent. This, of course, inspires the question of... at what point a law firm becomes a (mere) insurance defense firm, regardless of its size and sense of self-importance. And if they don't have enough work that they can truly specialize in defense litigation, is it really true that they will be more competent in serving their clients?

I am presently helping a plaintiff's lawyer with a case being defended by the self-insured defendant's business firm, rather than an insurance defense firm. Beyond the stunning ability to fell trees and produce ridiculous motions, I'm not clear on how the client is advantaged... unless paying much larger legal fees than necessary is deemed an advantage. It's great, I suppose, that this firm is able to produce novel interpretations of statutes and court rules that its lawyers haven't encountered before, but a second year associate at a (mere) defense firm would be able to set them straight about how a court is likely to resolve the motion.