The stately regatta that is The Am Law 100 kept sailing at a good clip in 2016, but is starting to encounter some unpredictable conditions.

The 2016 Am Law 100 results were rather impressive for an industry facing a number of headwinds, not least of which was flat demand for their lawyers' time. As a group, the nation's largest firms managed to grow revenue by 4.3 percent, compared to 2.7 percent a year ago. And profits per equity partner rose by 3.0 percent, slightly behind last year's 3.9 percent increase.

But a slowdown in the growth of revenue per lawyer may portend trouble ahead for a growing number of firms. RPL, long believed to be the most reliable single indicator of a law firm's financial health, increased a mere 1.5 percent, the second lowest increase in RPL since 2011. That broadly disappointing number, however, is driven by another ongoing story in Big Law: increasing stratification among firms. The country's largest firms are still experiencing healthy growth in RPL while that figure is on the decline for their smaller competitors.