MLB.com provides a very detailed look at what needs to happen on the last day for teams on the bubble to make the playoffs, and for teams to capture particular seeds. The Brewers Cardinals game is huge, as the winner of that contest is in. The Giants and the Phillies need a lot to go right to make the cut. As for the Cardinals Monday doubleheader:

They will not be made up if the only thing left to settle is seeding that has no impact on home-field.

MLB.com

So I don’t know what happens if the Reds win and the Cardinals lose. That would give the Reds second place in NL Central, with the Cardinals and Brewers tied at .500, and possibly SF tied at .500. SF loses the tie breaker to both teams. Playing two on Monday might give St. Louis the seventh instead of the eighth seed, but that has nothing to do with home field advantage. We’ll see.

If the Blue Jays win and the Yankees lose, I believe they need to go to the last 20 intradivision games tie-breaker. The Yankees are 11-9, Toronto 14-5 plus today. So Toronto clinches second with a win and a Yankees loss.

In the AL Central, the White Sox hold the tie-breaker over the Twins, and the Indians hold the tie-breaker over the White Sox.

The Astros will end up with a six seed, and may get there with a losing record.