All three National League Central postseason contenders played on the evening of Tuesday, September 22, 2015.
- The first-place St. Louis Cardinals defeated the visiting Cincinnati Reds, pushing the Redbirds' win total to 95 on the year.
- The second-place PIttsburgh Pirates beat the Rockies, which shrank their wild-card magic number to one.
- The third-place Chicago Cubs topped the Brewers behind Jake Arrieta.
Because all three clubs won, the Cardinals' lead in the division standings remains unchanged. But their magic number dropped by one and their odds of winning the division per Fangraphs increased.
Let's have a look at the NL Central postseason snapshot after the games of Tuesday and entering play on Wednesday, September 23, 2015. Each of the Cardinals, Pirates, and Cubs has 11 games to go on the 2015 regular-season slate.
I included the Fangraphs playoff odds, which are rendered like this:
The FanGraphs Playoff Odds are an adaption of the coolstandings.com playoff odds originally created by Greg Agami and Sean Walsh. To generate the playoff odds we simulate each season 10,000 times.
I used the Fangraphs projection mode for the playoff odds, though there are other options. This mode "uses a combination of Steamer and ZiPS projections and the FanGraphs Depth Charts to calculate the winning percentage of each remaning game in the major league season."
I added the Cardinals, Pirates, and Cubs' so-called magic numbers to the graphic as well. This represents the sum of eam wins and opponent losses necessary for that team to finish ahead of the opponent in the standings. I used the following formula:
Magic Number = 162 + 1 - (Team Win Total) - (Opponent Loss Total)
For fun I included the magic numbers for St. Louis, Pittsburgh, and Chicago against all postseason contenders, including the Los Angeles Dodgers and New York Mets, who are currently in first place in and likely to win their divisions. More substantively, it illustrates how close the Cardinals are to potentially sealing home-advantage in the NLDS and, if they should happen to make it that far, the NLCS. St. Louis is actually closer to a mathematical certainty of finishing with a better record than the Dodgers and Mets than they are the Pirates or Cubs. This Central race is amazing.