There has been much speculation in Washington circles about what it means that Tom Donilon has replaced James Jones as national security adviser. My hunch is: not much. I am not particularly persuaded by theories that hold that Donilon is more left-wing than Jones, and that he will clash more with senior generals. Jones, after all, was not exactly an outspoken advocate of the surge in Afghanistan (or for that matter in Iraq).

My sense is that a lot of the reason why he was appointed, even though Obama had barely met him, was so that Obama, who has no experience in military affairs, would have a high-profile retired officer on his staff who could with credibility stand up to the Pentagon. Jones made news in the summer of 2009 when he warned Gen. Stanley McChrystal that any further troop requests would be a “whisky tango foxtrot” moment for the White House. McChrystal asked for more troops anyway, because they were necessary. Most of his request wound up being granted not because of any decision made by Jones or by Donilon, who was then deputy national security adviser but widely seen as the power behind Jones’s throne. The ultimate call was made, unsurprisingly, by Barack Obama himself. That’s the way it always is and always has to be. The president is the “decider in chief.”

A good national security adviser can help marshal the information the boss needs to make good decisions and then help to implement them, but it is extremely rare for a national security adviser to be a major power in his or her own right. Henry Kissinger and Zbigniew Brzezinski are notable exceptions to this rule, but there haven’t been many others — and it has been many decades since they were in power. Usually, the national security adviser is a reflection of the president. This was certainly the case with Condi Rice, who was widely faulted for not doing a better job of getting the Bush administration to march in lockstep behind the president’s policies. That failure was ultimately not hers but George W. Bush’s. It was he, after all, who appointed her and gave her the power she had — or didn’t have. So, too, it will be with Donilon. He is certainly not a foreign policy intellectual like Kissinger or Brzezinski; he is a consummate staffer. There’s nothing wrong with that. But what it means is that we shouldn’t expect much change from his appointment.