So knowledgeable of the sweet science was Siler, that he refereed the James J. Corbett-Bob Fitzsimmons heavyweight championship fight and then filed a story about the contest as chief correspondent for the Chicago Tribune. Corbett later criticized Siler for a slow count when he dropped Fitzsimmons in round six.
Siler began officiating when gloved boxing and the Marquess of Queensberry rules were first being introduced. Known for his honesty and integrity, Siler declared Joe Gans the lightweight champion of the world when he disqualified Battling Nelson in the 42 round of their 1906 bout.
Among the other notable fights Siler officiated were match-ups between Fitzsimmons and Jim Jeffries, Fitzsimmons and Peter Maher and Terry McGovern and Pedlar Palmer.