Ambassadors are to international politics what first-base coaches are to baseball: While they're undeniably important, their accomplishments (or failures) tend to go unnoticed. Their job is to attract as little attention as possible and be a team player.

Nevertheless, a case can be made that Gary Locke—who has announced his resignation as U.S. Ambassador to China—has been the best U.S. ambassador to China since Sino-American relations were restored in 1979.

In a way, this isn't surprising: Locke, once considered a possible presidential contender, was arguably the most accomplished politician to ever occupy the post, having served as both the governor of Washington state and as the U.S. Commerce Secretary. But his tenure in Beijing may ultimately be considered the highlight of his career, and may serve as a blueprint for how to manage Sino-American relations going forward.

Locke became the 10th U.S. ambassador to the P.R.C. in July 2011, after his predecessor, Jon Huntsman, resigned to run for the 2012 Republican Party presidential nomination. The president tapped Huntsman for the post in 2009 for a variety of reasons, not least the belief that the ambassador would be the most formidable challenger to Obama's re-election chances in 2012. (As it turned out, Huntsman—in part because of his association with the president—finished a distant fifth in the GOP field).

The handsome, Chinese-speaking Huntsman, who learned the language while serving as a Mormon missionary in Taiwan, had once seemed to be an ideal fit for the job. But his tenure as ambassador suffered from an incident in February 2011, when he inserted himself into small, anti-government demonstration in Beijing.