The matter of season tickets for the series of base ball games to be played by the Indianapolis Club in (St. Louis) has given rise to considerable question. On the arrival in St. Louis of Mr. Scott, on Tuesday last, it was announced that the sale of season tickets was a fixed fact. But as none have been offered for sale, the inquiry has naturally been made as to the reason for their being withheld. Mr. Scott explains the matter very satisfactorily, as follows: After canvassing the ground thoroughly on Tuesday and Wednesday of last week, he arrived at the conclusion that it would be far better to rely upon the direct gate patronage of the patrons of the game than to sell tickets in advance. This conclusion he reported to Mr. Pettit on his arrival, and that gentleman at once indorsed his decision. The friends of base ball will understand this straightforward policy of the managers, and will show their appreciation of fair dealing by a liberal patronage on each day of play.
-St. Louis Globe-Democrat, July 13, 1878
I'm intrigued by the statement that the decision regarding ticket sales was made after "canvassing the ground thoroughly..." It's possible that the Indianapolis Club had made a decision to play their remaining home games in St. Louis (although that's far from certain) but after an inspection of the Grand Avenue Grounds, which was operating under a smaller configuration than it had in previous seasons, decided that the ballpark did not meet their expectations or needs. While speculative, it's possible that the state of the ballpark combined with what Al Spink described as poor attendance for the series against Boston convinced Pettit that St. Louis would not be an improvement over the situation in Indianapolis.