The story they were pushing was that the only way to continue to increase profits per partner is to focus solely on the high end, high dollar work. Part of the way to do this is to sell into the biggest legal markets (NY, DC, London). But the other lesson was these firms could then do the same in other large, secondary markets because of the strength of their reputations. This would bleed high end work that had previously been done by the super regional firms (basically the big fish in places like Atlanta, Houston, etc.).
The bottom line was that the super regionals were told they either needed to jettison their underperforming practices (things like wills & estates and employment), double down on high end practices (M&A, bet the company litigation) and expand or take a long slow ride down the profitability curve. It was hard thing for a lot of these firms to hear since they had prided themselves on being "full service" firms, which in a previous era was the way forward. In short, they were Sears in the 1970's and 1980's - selling everything under the sun but not capturing the high-end consumer - and being told they needed to become Restoration Hardware.