Reggie Otero, manager of the Triple-A Havana Sugar Kings from 1954–1956 and later a longtime coach for the Cincinnati Reds, saw Nelson clobber major league pitchers while playing winter baseball in Cuba.
While playing winter baseball in Cuba during his time as manager of the Triple-A Havana Sugar Kings (1954-1956) and as a coach for the Cincinnati Reds, Reggie Otero observed that Nelson was particularly effective against major league pitchers.