Gelof went 2-for-4 with a solo home run and a stolen base in Wednesday's 6-3 loss to the Mariners.
He took George Kirby deep in the fourth inning to get Oakland on the board, but Gelof's squad was already down 2-0 at that point. The rookie second baseman is batting .310 (22-for-71) in September as he puts the finishing touches on an impressive MLB debut that has seen him rack up 13 homers and 13 steals in just 59 games.