The recent move by DLA Piper's former global chair Nigel Knowles to fast-growing national U.K. firm DWF is one of the most intriguing lateral hires in years.

It is not just extremely rare for Big Law management partners to join another firm; it is almost unprecedented.

In fact, I can only come up with one other example where such a move involved the partner taking up a firmwide management role at their new home: Linklaters' longtime managing partner Tony Angel joined DLA as global co-chair and senior partner in 2011.