National League Playoff Scenarios: Sep 24 2020

The National League playoff race is especially close this year. Currently, there are six teams fighting for four spots. The playoff scenarios this year are extremely complicated at this point. The Cardinals, Giants, Reds, Marlins, Brewers, and Phillies all have a shot at making the playoffs. Even crazier, every single one of these teams has a shot at taking the fifth seed in this year’s playoffs.

I wanted to run a few simulations to gauge the likelihood of each team making the playoffs. I will begin with a ‘big picture’ playoff race giving each team a percentage change at making the playoffs.

Then, I will go through each of the six interesting teams and discus their different possible scenarios. For instance, I will give the conditional probability the Reds make the playoffs if they win 0, 1, 2, or all three games in their weekend series. That way you can know ‘if my team wins 2 more games, I have a _____ shot at the playoffs’.

If you want to jump ahead to a specific team’s discussion section, please follow the links below: Cardinals, Giants, Reds, Marlins, Brewers, Phillies.

Methodology

Because everything is so fluid, I decided the easiest way to go about things was to model every single upcoming game as a complete tossup. That is, in every remaining game, I gave each team a 50% chance of winning. Then, I simulated the remaining schedule 10000 times and counted how many times a team made the playoffs. The percentage of simulations in which a team makes the playoffs is the number I report as ‘playoff percentage’.

First, a comment about giving each team a 50% chance to win. I have discussed in my article about building a mathematical model that building a model should go through iterations and refinements. The first step in any model is to get the simplest possible thing that works and delivers valuable insights.

While I could look at potential pitcher matchups, home/away splits, and other minutiae in order to adjust the winning percentages in any given game away from 50%, I don’t think that approach is particularly valuable here. You can even look at the quality of matchup for each of these teams and they are roughly equal. Sure the Reds and Giants must play the Twins and Padres, respectively, but I don’t think that will make too much of a difference in their playoff chances.

One could equally validly view the number ‘Playoff Chances’ below as ‘percentage of possible season trajectories in which my team makes the playoffs, assuming all outcomes are equally likely’.

2020 Playoff Format

Because of the intricacies of the COVID season, I should mention how the playoff teams are determined this year.

The top 2 teams in winning percentage in each division are guaranteed a playoff spot. Then, the next two best teams in winning percentage in each league get a playoff spot. Because some teams (like the Cardinals, for instance) will play fewer games, we must use winning percentage rather than just wins to determine the playoff teams.

Now, because of shortened season, ties are much more likely. In fact, things are extremely close this year in the National League and so ties are almost a guarantee. As of writing this, there is a three way tie for fifth, then a half game back is the Marlins, then another half game back is a two way tie for ninth in the league.

In the event of a tie, the first tie-breaker is head to head record. The second tie breaker is a team’s division record. If we need more tie breakers (which we might, many teams are clustered around a .500 division record), we simply look at a team’s last 20 division games.

There are considerations for three-way ties and other unlikely events, but I will not go into depth on those here.

League-Wide Playoff Chances

The current standings of the teams involved are as follows:

Team	W	L	W%
Dodgers	39	17	.696
Braves	34	22	.607
Padres	34	22	.607
Cubs	32	24	.571
Cardinals	27	26	.509
Giants	28	27	.509
Reds	29	28	.509
Marlins	28	28	.500
Phillies	28	29	.491
Brewers	27	28	.491

After running 10,000 simulations, I have found the following results for the chances of each team making the playoffs.

Team	Playoff Chances
Dodgers	100%
Braves	100%
Padres	100%
Cubs	100%
Reds	93.3%
Giants	81.2%
Cardinals	81.2%
Marlins	79.8%
Phillies	37.6%
Brewers	27%

Before breaking off into individual scenarios for the six teams still fighting, I should offer a comment. You can compare our results with the results of another popular modeling site, 538. Their playoff chances appear a bit different. The reason for this is 538 models probabilities based on specific matchups using ELO ratings. Therefore, for instance, the Reds might be given a 45% every game against the Twins instead of 50%.

What 538 doesn’t offer though, is the conditional chances based on how many teams your game wins. We’ll go through the six teams without a guaranteed playoff spot and determine their playoff chances if they win 0 games, 1 game, etc.

Individual Team Conditional Playoff Scenarios

Cincinnati Reds

My model assigns the Reds a 93.3% chance at making the playoffs overall. If I force the Reds to win 0, 1, 2, or 3 games out of the final three, here is how those percentages change:

Reds’ Wins in Last 3 Games	Playoff Chances
3	100%
2	100%
1	97%
0	45.4%

This suggests the Reds’ simply need to win at least one game in order to have a guaranteed playoff spot. Interestingly, there is a fairly likely scenario when the Reds get swept yet still make the playoffs. This is because the Reds will likely hold the wild-card against either the Brewers, the Phillies, the Marlins, and the Giants.

Milwaukee Brewers

The Brewers and the Cardinals have an extremely important 5 game series coming in the next 4 days. Because the Brewers are down by a game to the Cardinals, they essentially need to win 4 out of 5 to overtake them. Here is the Brewers’ playoff chances based on number of wins

Brewers’ Wins in Last 5 Games	Playoff Chances
5	100%
4	99.3%
3	29.3%
2	1%
1	0
0	0

Notice how quickly their chances drop off if they don’t win this series by more than one game.

St. Louis Cardinals

The Cardinals are in pretty much the opposite situation from the Brewers. Being up a game, they really only need to win 2 to be almost guaranteed a spot.

Cardinals’ Wins in Last 5 Games	Playoff Chances
5	100%
4	100%
3	100%
2	99%
1	1%
0	0%

Talk about controlling your own destiny. The reason the Cardinals are still so likely to make the playoffs even if they lose this series 2-3 is because they hold the tie breaker over the Reds, the Giants, (probably) the Marlins, and the Brewers. They will beat the Brewers straight-up for a wild card spot if they win 2 games. So in this scenario, they only miss the playoffs if every other team of the Reds, Cardinals, Giants, Brewers, Phillies, and Marlins finish over .500

San Francisco Giants

The Giants are fighting for a wild card spot because their division is loaded. The top 2 teams in the West are so far ahead they have already secured their spots. The Giants’ are already a half game over .500 and it looks like .500 will do it to sneak into the playoffs.

Giants’ Wins in Last 4 Games	Playoff Chances
4	100%
3	100%
2	49%
1	0%
0	0

Philadelphia Phillies

It is fairly unlikely for the Phillies to make the playoffs by virtue of finishing second in their division. This is because the Marlins have a half game edge on the Phillies and hold the tie breaker. Therefore, the Phillies best bet (not the only way, though) is to take one of the wild-card spots.

Phillies’ Wins in Last 3 Games	Playoff Chances
3	100%
2	59%
1	6.5%
0	0%

Miami Marlins

The Marlins have the benefit of being in second in their division so they only need to beat out the Phillies. Moreover, the Marlins have the head-to-head tie breaker with the Phillies so the Phillies need to do better than finishing with the same record as the Marlins. The Marlins’ playoff chances are pretty good.

Marlins’ Wins in Last 4 Games	Playoff Chances
4	100%
3	100%
2	92%
1	50%
0	14%

A NOTE on 100%

I will point out here that 100% does not mean that there is no conceivable way that a specific team will miss the playoffs. Similarly, 0% does not mean there is absolutely no chances that a team makes the playoffs. Rather, it means that out of the number of simulations I ran, the team either failed to miss or failed to make the playoffs every time. There are always corner cases and extremely unlikely events that will become more evident as time goes on.