WHY AN OBAMA WINS MATTERS…. Depending on your perspective and scorecard, most observers seem to think either Obama won a narrow victory in the debate, or McCain won a narrow victory. It’s worth remembering, though, that the larger political context suggests neither result gave McCain what he needed.

Remember, McCain went into the debate moving in the wrong direction. Recent polls show him falling behind, the “suspend the campaign” gimmick was largely a flop, and as voters’ attention moved to the economy, the race quickly shifted to McCain’s weakest area.

Given this, last night was a genuine opportunity for McCain. The debate was focused largely on foreign policy and national security, issues perceived as McCain’s strength by voters, the media, and McCain himself. It was, in this sense, an event that McCain could use to turn the whole campaign around.

Except, that clearly didn’t happen. Whether it was a tie or a slight win for either candidate isn’t especially important — McCain needed a clear, dominating victory. He didn’t get one. Not even close.

For Obama, the dynamic is reversed. He’s benefitted as the race has shifted to the economy, but he needed to demonstrate last night that he’s a credible, knowledgeable figure on foreign policy, ready to go toe to toe with a candidate with a more extensive background in international affairs. And, he did.

Usually, describing someone as having “held his own” sounds like underwhelming, or possibly even a mild insult. But in this case, saying Obama “held his own” against McCain on foreign policy and national security isn’t such a bad thing at all. For a lot of people, at home and in the media, McCain was the only candidate in the race who could speak with any authority on these issues. Obama proved them wrong.

(For the record, I thought Obama more than “held his own” on foreign policy. Like Fred Kaplan, I actually saw Obama as being far stronger on the issue. I mention the “held his own” meme, because it seems to have quickly become part of the conventional wisdom.)

McCain needed a big night to turn things around, and he didn’t get it. In this context, no matter how close viewers perceived the debate, it was a missed opportunity for a candidate who won’t get too many more chances to change the race.

Steve Benen

Follow Steve on Twitter @stevebenen. Steve Benen is a producer at MSNBC's The Rachel Maddow Show. He was the principal contributor to the Washington Monthly's Political Animal blog from August 2008 until January 2012.