The Chicago-St. Louis game to-day was characterized by the heaviest kind of batting both sides, Dorgan, Hines, Clapp, Spalding, and Peters leading. It was a very exciting contest up to the seventh inning, when a very wild throw by Hines let in two runs, and gave St. Louis a lead which was retained to the end. Blong started in to pitch, but Nichols relieved him in the second inning after Peters, Hines, and Spalding had made safe hits. Nichols proved quite effective, Anson striking out twice. The play of the visitors in the field was loose, passed balls resulting from wild pitching causing McVey and Anson to change places in the sixth inning. Peters played a perfect game at short, but Spalding, Glenn, and Eden committed the costly errors which lost the game. The St. Louisians gave a sorry exhibition of outfielding, all but Dorgan, but the infielders did better, Croft's display at first being the best seen here this season.
-Chicago Tribune, August 26, 1877
According to Jon David Cash, Brown Stockings' officials were tipped off about the events of the 24th by the actions of umpire L.W. Burtis, who acted as the middleman between the Chicago gamblers and the St. Louis players. Cash writes that "The directors of the St. Louis club had cautioned Brown Stockings' captain Mike McGeary about the conspiracy. In the next day's game, McGeary 'made a judicious change' when it appeared that one of the players 'attempted to duplicate his errors (of the previous day).' By transferring the suspected player 'to a position where, as luck happened, he had little to do,' McGeary also alerted the other conspirator about the suspicions of the team's management. " St. Louis won the August 25th game by a score of 12-8.
It's obvious that the player who was judiciously moved was Joe Blong. St. Louis had jumped to a 3-0 lead after the first inning and Blong was removed in the second as he tried to give the lead back. While Chicago scored four runs in their half of the second, the Tribune piece makes it sound as if the runs scored after Blong had been switched to center field. While I don't have any more specific information about what transpired during the inning, we can say that, with a 3-0 lead, Blong gave up three hits before being removed from the mound and this contributed to Chicago scoring four runs.
McGeary's role in all of this was brought up by the Chicago papers, largely because of the accusations made earlier by Devinney. However, it seems rather clear that, once informed by management that something was up, McGeary kept a close eye on Blong and Battin and took steps in the August 25th game to make sure that the events of August 24 were not repeated. It seems reasonable to suggest, based upon his actions of August 25, that McGeary was not part involved in the conspiracy to throw the games against Chicago.