A first-round pick in the 2012 Major League Baseball entry draft, the 22-year-old Seager was unanimously selected for the honor by the Baseball Writers' Association of America.
Seager hit .308 with 26 home runs, 72 RBIs and 105 runs scored in 157 games this season. In two playoff series, he batted .205 with two home runs and four RBIs. His 72 RBIs led all rookies in the majors.
The 23-year-old Fulmer posted an 11-7 record with a 3.06 ERA and 132 strikeouts over 159 innings in 26 starts in 2016.
A first-round pick of the Mets in the 2011 draft, Fulmer was traded to Detroit in the July 2015, deal that sent star outfielder Yoenis Cespedes to New York.
Fulmer led all AL rookie pitchers in wins and innings pitched.