National League finalists, along with Arenado, are the Giants' Matt Duffy and the Reds' Todd Frazier. LeMahieu's competitors at second are the Marlins' Dee Gordon and the Reds' Brandon Phillips -- who has won four in his career, the latest in 2013.
Should Arenado prevail, he would join the Red Sox's Frank Malzone (1957-59) as the only third basemen to take the award in their first three Major League seasons. The award was established in 1957, and Malzone was the first American League winner.
According to Fangraphs, Arenado's ultimate zone rating (UZR) -- which the site values as more instructive than fielding percentage because it calculates defensive events in terms of runs saved or lost -- was 5.