According to the NBA’s press release:
Jennings guided the Bucks to a 2-0 record to start the season, a first for the team since 2005-06. Jennings led the league in assists (13.0 apg) and paced the conference in steals (4.0 spg), while finishing third on the team in scoring (17.0 ppg). He recorded point/assist double-doubles in consecutive games for the second time in his career, hitting a game-winning 3-pointer against the Cleveland Cavaliers on Nov. 3. His 13 assists in each game tied his career high.
The Jennings/Ellis backcourt is still searching for chemistry — see, for example, the Bucks’ the two-possession, all-airball attempt to milk a small lead at the end of the Cavs game. But the Bucks sit atop the Eastern Conference, and Jennings has been notching career-highs in assists and steals left and right, so this award can’t be too much of a surprise. He currently leads the league in both assists per game and steals per game.
In all likelihood, Carmelo Anthony — of the similarly 2-0 Knicks — garnered consideration for the award as well. He was mentioned as one of five Eastern Conference honorees, along with Anderson Varejao, Glen Davis, Kemba Walker, and Chris Bosh.