I love reading about how some of the old-timers got their nicknames. Just looked this one up for "Baby Doll" Jacobson...

After playing in the minor leagues for the 1911 season, Jacobson was signed by manager John McGraw of the New York Giants. In early April 1912, McGraw turned over Jacobson to the Mobile Sea Gulls of the Southern Association.^[7] On opening day of the 1912 season, the band began playing the popular song, "Oh, You Beautiful Doll", as Jacobson came to the plate. Jacobson recalled, "Well I led off with a home run on the first pitch and a lady sitting behind the plate jumped up and shouted, 'You must be that beautiful doll they were talking about.' The name stuck with me and that was it."