What is it with the mid-tier, that much-maligned but ill-defined group of law firms that always gets it in the neck from consultants, pundits and journalists? Written off whatever the conditions of the day, observers of the legal industry will usually be told this breed will soon be history as an over-supplied and fragmented market is carved up between industry leaders and nimble boutiques.

While there is a grain of truth here – which we'll get to later – it's usually stretched to the point of woolly nonsense delivered with shaky reference to the facts.

For a start, who is this group supposed to be? Taken literally you could make a solid case that any firm south of Slaughter and May is mid-tier, though that isn't usually what is meant. Smaller than Ashurst, maybe? Consensus starts to break down. Outside the top 50? Take your pick. There are a bewilderingly large number of mid-tiers out there. In an industry obsessed by relative status, groups are defined as much by what you're not – so the mid-tier is, for many a firm, someone else.

But for argument's sake, let's call it the top 50 City firms generating less than £100m. Far from this group having had a bad recession, they have tracked the top 50, as a whole doing slightly worse than average in 2008-09 and slightly better in 2009-10. There is some truth that there are benefits of scale and greater stability in reaching a certain size, but looking at law performance in recent years that point appears to be £70m-plus for a domestic practice and £250m-upwards for a firm wanting to operate internationally.

Over-lawyered? I've never known what is meant by that. If you're an aspiring barrister trying to gain a pupillage, the profession certainly looks over-lawyered, but for practitioners in general and for clients, there's rarely much flesh put on the bones of such claims.

There is more to the argument that law is a fragmented industry in which service providers struggle to differentiate themselves. Yet in many ways, this is true in many tiers, from magic circle through to regional insurance shop, rather than the mid-tier-specific malady it's often made out to be. And, as for the joys of market differentiation, ask the average business-person what separates the big four accountancy firms – unquestionably a consolidated industry – and see what you get.

None of which is to pretend that firms in the top 25-50 range don't have their fair share of challenges. But the desire for very broad observations that can be used to sum up the market often say rather more about the observers than the observed. A competitive market will not conform to such generalisations and success and failure will typically be defined far more by individual performance and luck than a particular business model, whatever you call it. Even for the unloved mid-tier.