Kelly, naturally a first baseman, saw regular time as a second baseman in 1925 when Frisch injured his hand, while backup Bill Terry began playing first base. With the emergence of Terry, who requested a trade so that he could receive more playing time, and Giants manager John McGraw desiring an improvement in the outfield, Kelly was traded to the Cincinnati Reds prior to the 1927 season for Edd Roush. The Reds traded Roush due to a contract dispute. With Wally Pipp at first base for the Reds, Kelly was slated to play center field. The Reds released Pipp before the 1929 season, and Kelly returned to first base.