Yes, Larry Summers is Leaving: Summers cast his eye on the Fed chairmanship and agreed to bide his time until Ben Bernanke's term ended at the NEC--a staff position well below his old job as Clinton's Treasury secretary...
"Below." "Above." Joshua Green is old enough to know that whether the Secretary of the Treasury is "above" or "below" the Assistant to the President for Economic Policy really depends on the people and on the President. Does anybody think that Secretary of State William Rogers was "above" Assistant to the President for National Security Henry Kissinger? Does anybody think that Counselor to the President Daniel Patrick Moynihan was "below" Secretary of Health, Education, and Welfare Robert Finch? But does anybody believe that Treasury Secretarys George Shultz or William Simon were "below" John Ehrlichman? Does anybody think that Bush's first two Treasury Secretaries--Paul O'Neill and John Snow--were "above" anybody? And Hank Paulson, similarly, was a very weak Treasury Secretary ("Secretary of the U.S.-China Relationship and of the Nature Conservancy," was the saying) until the coming of the financial crisis and the paralysis of the Bush White House.
The rule is that with a President who is weak--or uninterested in economic policy--or when the Chairs of House Banking, Senate Banking, Senate Finance, and House Ways-and-Means are strong, then the Treasury Secretary is the more powerful position. But with a President who is strong and interested in economic policy, the Assistant to the President is the higher-ranking job.
This is an old, old story.
In the Dark Ages, there was a guy who was the king's "mare-scallus"--his "horse-slave," responsible for mucking out the stables and bringing the horse out when the king wanted to ride. But by the time of Richard de Clare, 2nd Earl of Pembroke (1st creation), his title as Marshal of England meant not that he mucked out the king's stable but rather that he arranged and regularized rights and duties in the feudal hierarchy, with power to "order, judge, and determine all matters touching arms, ensigns of nobility, honor, and chivalry..." Over the generations, face-time with the king is what matters for power.
Or consider the job held by Thomas Woolsey, Thomas More, Thomas Cromwell, and Richard Rich under Henry VII Tudor: Chancellor of England. Originally the chancellor was the cancellarius--the usher in the law court who sits at the lattice screen separating the judge and the advocates from the audience, and determines who can go in and who must stay outside watching. But by the Tudor dynasty the office of Chancellor was much more than just that of an usher who called out and told the people concerned with the next case that it was time for them to appear before the king. Once again, over the generations it is face-time with the king that is what matters for power.