What we know...
The Phillies hold a one-game lead over the Mets in the NL East and are the only team that controls their own destiny. A sweep over the Washington Nationals gives the Phillies the NL East title for the second straight season, no matter what else happens.
Milwaukee and the Mets are tied for the wild card.
All three teams are playing at home. The Phillies host the Nationals, the Mets host the Florida Marlins and the Brewers host the Chicago Cubs. The Nationals and Marlins have both been eliminated and have nothing to play for, with the possible exception of the Nationals fighting to avoid 100 losses; they have 99 now. The Cubs have already won the division and locked up home field advantage throughout the playoffs, so they're just looking not to get anybody hurt.
The Cubs could also take an interesting view of their series with the Brewers.
If the Phillies and/or Mets make the post-season, their aces - Cole Hamels and Johann Santana - would only be available to pitch once in the series, if they are needed to pitch on Sunday (which both are scheduled to do) to get their respective team into the post-season. If the wild card comes from the NL East, they would be the Cubs opponent for the NLDS and either club would be without their ace until later in the series. If the Brewers are the wild card, the Cubs would host the Dodgers in the NLDS, which might be more advantageous than facing the Mets or Phillies.
So, could the Cubs be "pulling" for the Brewers to win the wild card? And, if so, do they run a lineup of utility players and minor leaguers out onto the field this weekend?
Bad news for the Cubs would be if the Brewers fall out of the wild card race and the NL East is decided by Saturday. That would allow Hamels or Santana to pitch the opener of the NLDS against Chicago.
As for the Phillies. If they fall short of their desired sweep and the Mets finish tied with them for the division title, the Mets will win the division because of the tie-breaker (head-to-head games) and the Phillies would get the wild card, if the Brewers can't make up the one game that they trail the Phillies by.
If the Phillies, Mets and Brewers all finish with identical records, then the Mets would come to Philadelphia for a one game playoff on Monday, with the winner taking the division and the loser playing Milwaukee for the wild card. That game would be on Tuesday either in Philadelphia or New York.
Looking ahead to the NLDS - should the Phillies get there - they would have likely hose either the Brewers or Dodgers. The only way they would start on the road is if they were the wild card and had to go to Chicago.
So, with all of the possible scenarios to keep in mind, all the Phillies really need to know is that they control their own destiny and all they have to do is win and all will be right with the world. Short of that, they need to hope the words of Casey Stengel... "The Mets have shown me more ways to lose than I even knew existed."