With a schedule of a little over 100 games, most teams employed two regular pitchers, and the Providence Grays in the National League featured Radbourn and Charlie Sweeney.
According to the 1991 book Glory Fades Away by Jerry Lansche, Sweeney fell out of grace with the Providence team in late July after he refused to be replaced in a game while drunk, and was expelled.
Leveraging his situation, Radbourn pledged to stay with the club and be the sole primary pitcher if he would be given a raise and granted free agency at season's end.
For an encore, he also won all three games of 1884's version of the World Series, pitching every inning of a sweep of the New York Metropolitans of the American Association.
His performance in 1884, along with a generally strong career and an overall record of 309-194 (.614), assured Radbourn his place in the Baseball Hall of Fame.
The best hitter of the 1884 Union Association was Fred Dunlap of the Maroons, while star pitchers for the UA included Jim McCormick, Charlie Sweeney, Dupee Shaw and Hugh Daily.
Notable players that made their debut in the Union Association included Tommy McCarthy, who was elected to the Hall of Fame in 1946, and Jack Clements, the only man in baseball history to play a full career as a left-handed catcher.
The Union Association saw two no-hitters in its brief existence: one by Dick Burns of the Outlaw Reds on August 26 and one by Ed Cushman of the Brewers on September 28.
The established leagues changed their own rules via the Day resolutions [to enforce the reserve clause to ban players who played in the UA].