Any managing partner who is not a top-flight attorney is despised by the "real lawyers", and doesn't last long. He may be a transactional lawyer rather than a litigator, but he has to be good at his "real job" or he gets zero respect. And a managing partner with no respect is worthless at the job of managing the business side.
In addition, he also has to manage the cutthroat politics that always seem to be simmering just below a boil. What I meant by my statement is that the somewhat convoluted interpersonal politics on the USSC (see The Brethren if you can stand it) will be like a walk in the sun after the vicious stuff that a managing partner is used to dealing with on a daily basis.