What are the odds that the Nats reach the playoffs?

With the Nationals reaching .500 last night, several writers have noted that we’re only five games behind in the wild card race. (Of course, at this point in the season, being within five games in the wild card race is hardly a mark of distinction—10 of the 16 NL teams are within five games of the lead in either their divisional or the wild card race.)

I thought I’d take a peak at the playoff odds. First, I checked out coolstandings.com. The site reports that the Nats have an 18.5% chance of making the playoffs—a 5.5% chance of winning the division and 13.0% chance of winning the wild card. Those odds sound mighty good.

Then I remembered that Baseball Prospectus also posts playoff odds. The story is dramatically different on that site—the Nats’ chances of reaching the playoffs are only 0.6%—0.1% for the divisional title and 0.4% for the wild card.

How could the odds of the same event be so different on these two sites? Obviously, the two sites make very different projections for the rest of the season. On coolstandings.com, the team’s expected W-L record was 83.6–78.4, while on Baseball Prospectus it was 75.8–86.2.  coolstandings.com expects the Nats to win at a .530 clip for the rest of the season, while Baseball Prospectus expects a .441 winning percentage.

Details on how the two sites construct their forecasts are sketchy, but coolstandings appears to rely mostly on the team’s year-to-date runs scored and runs allowed, whereas Baseball Prospectus says that its odds are based on depth charts at the beginning of the season, which are supplemented by the team’s actual performance as the season goes along. Apparently, the BP depth charts really don’t like the Nationals.

It’s disconcerting to see two such sophisticated sites presenting such disparate odds. It really isn’t clear to me which one is more nearly correct. I imagine that the truth is somewhere in the middle, but with such a wide range, that isn’t much help.