Does the new playoff format help or hurt the Nats?

On Friday,MLB announced the addition of two more wild card teams, with the each league’s pair of wild cards facing off in a one-game contest. How does the new format affect the Nats’ post-season chances in 2012?

It’s obvious that the probability of the Nats (and of every other team in baseball) making the post-season goes up. But how much does it affect the Nats relative to other teams? And how does it affect their chances of winning the World Series?

First, a quick analysis of the main features:

• The probability of the divisional champions winning the World Series, to a first approximation, isn’t affected. For example, if all teams making it to the post-season were of equal quality (a convenient starting assumption), the probability of divisional champions winning would have been 1/8 under the old format and remains 1/8 under the new format. A second-order effect is that divisional champs will probably pick up a slight advantage by having a better opportunity to optimize their pitching rotations compared to the wild cards, who will need to use one of their best pitchers for the one-game playoff. So a small net advantage to the divisional champs.
• The probability that any wild card team wins the World Series would also remain at 1/4 (assuming equal quality), but since there are now twice as many wild card teams, the probability of a particular wild card team winning is now only half as big (1/16 instead of 1/8).
• Therefore, if a team is more likely to be the league’s first wild card, the new format substantially hurts its World Series chances, whereas if its more likely to be the second wild card, it boosts the team’s World Series chances.

The chances of being the league’s first or second wild card team depend on how good the team is and what division it’s in. A team is more likely to be the first wild card team if it’s playing in a division with an even stronger opponent, since the team playing in a weak division would simply win the division.

The CAIRO projections that are available from the Replacement Level Yankees Weblog show the Nats’ post-season probabilities under one set of assumptions. The good news is that RLYW sees the Nats as a pretty good team, projecting 86 wins, second in the NL East to the Phillies, who are projected at 92 wins.

The interesting thing about those projections is that they also include post-season probabilities based on computer simulations. According to CAIRO, the Nationals’ probability of making the post-season went up from 37% under the old format to 46% under the new format. The projections also show the Nats as much more likely to make the post-season as the first wild card team (18%) than as the second wild card team (9%). The have a 19% chance of winning the division outright.

The implication is that—under these assumptions—the Nats’ probability of winning the World Series is lower under the new format than it would have been under the old format. Because the Nats play in the division with the league’s strongest team (the Phillies) and there are many more teams competing for the second spot, their probability of being the first wild card team is much better than their probability of being the second wild card, meaning that their World Series probability is reduced.

Of course, these probabilities are heavily dependent on the projections being used. An alternative is Baseball Prospectus, which projects the Nats at 84 wins, but only fourth place in the NL East. A small difference in projected team quality will imply a fairly large difference in playoff probabilities.

The other comment I’ll make is that the Nat really should consider putting Strasburg on a once-a-week schedule to make him available for the post-season, especially the one-game playoff. I simply don’t buy the argument that pitching on six days rest would be more stressful than pitching the same number of starts on four days rest. Teams will quickly learn that the optimal strategy for a wild card team is to have their best pitcher available for the wild-card all-or-nothing game. While the post-season often has other all-or-nothing games (for example, game seven of a league championship series or a World Series), the wild-card series is unique in that it can be planned for.

Adam Kilgore of The Washington Post provides some additional thoughts on how the new format affects the Nationals.