Cincinnati Reds out of the Wild Card
The Reds and the Cardinals go head-to-head 6 more times before the end of the year. As of the beginning of the day on September 5th, the Reds are tied with the Arizona Diamondbacks for the final Wild Card spot in the National League. Due to tiebreakers, the Reds would actually be out of the playoffs, all else equal.
Cincinnati may want to take advantage of a weak schedule to close the year (9 games against Detroit, New York Mets, and Pittsburgh), but the Cardinals could very easily ruin the young Reds' fun. The 6 remaining games will be split evenly between Great American Ballpark and Busch Stadium. Should the Cardinals at least split the 6 games, the Reds' path to the playoffs may become harder.
According to Tankathon, the Reds have the 6th easiest schedule remaining while the Diamondbacks have the 9th easiest schedule, per opponents winning percentage. For what it's worth, the Cardinals have the hardest schedule remaining. Should the Cardinals flip the script and make the Reds' final month more challenging, they could keep Cincinnati out of the playoffs after an exciting regular season.