They're two celebrities—Baldwin basically playing his 30 Rock character Jack Donaghy and Krasinski his Jim Halpert from The Office—acting out the Yankees-Red Sox rivalry as a real-life competition between friends. Er, friends who are enemies when it comes to baseball.
Whatever you call them, the ads are wonderfully written and beautifully shot in black and white and they're actually done to promote New Era's officially licensed Major League caps and gear.
But the sales pitch plays most of all on the trash-talking between these two frenemies and the rivalry between their teams on the field.
Take a look at all five of the ads that have been released so far, including the hilarious new spot, titled "912."