The Astros are a virtual lock for the playoffs this year, but they need to stay ahead of the Red Sox. If they maintain the lead of the Red Sox, then they will have home-field advantage in the ALDS and ALCS. The only NL team that would have home-field advantage over the Astros would be the Dodgers.
The Astros have 38 games left in the season, and the bullpen is looking better. With Will Harris on a rehab assignment, the bullpen is about to get one of their main cogs back. With September approaching, they will be able to add some additional arms to the bullpen when rosters expand.