2024 College Football Playoff Format: How Format Affects Winners
The 2024 college football playoff format is changing yet again. In this sport, it seems like no matter what you do, somebody feels like they didn’t get a fair chance. The point of the playoffs is to ensure the best teams win. But did it ever occur to you that the playoff format itself has a huge impact on who wins?
Some playoff formats help the favorites, some lead to chaos (or madness). Some give chances to anyone who reasonably deserves it, some are quite stingy with who gets a shot.
The 2024 college football playoff format is as follows:
- The playoff will be 12 teams instead of 4
- The top 4 teams get a BYE
- 6 highest rated conference champions + 6 at-large bids
- Debate on whether to adopt “5+7”, 5 power conference champions and 7 at-large bids.
With the college football playoff format expanding and changing yet again heading into the 2024 season, there is no better time to look at sports playoff formats. How do different sports playoff formats impact title odds? If you’re the favorite, what should you prefer?
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Features of Different Playoff Formats
Quickly, we’re going to look at ways that playoff formats can differ among sports. Then, we’ll talk about which features help or hurt the favorites. More generally, we’ll talk about how the attributes of a playoff format impact the predicted outcome.
Number of Teams
The first and perhaps most important feature of a post-season tournament is the number of teams that compete in the tournament. This can vary wildly between sports.
For example, in college football up until 2023, only four teams made the playoffs. In professional baseball, basketball, and football roughly a third to a half of the league makes it, somewhere around 15 teams. In college basketball, though, 68 teams make the tournament.
The bigger tournaments deemphasize the regular season. In smaller tournaments, you need to ensure that your regular season performance is on point. It might be pretty easy to predict how this playoff format feature impacts championship probabilities, but we’ll save that for later.
Best-of-X
The second most important factor of a tournament is how many times teams play in order to determine a winner. Sometimes, one time is enough. More often, though, teams will play multiple times to determine a winner.
In the NFL, college football, and college basketball, one game determines who advances. This leads to drama, pressure, and pretty good media spectacle.
In baseball and professional basketball, the winner is determined by the outcome of a series. Typically 3, 5, or 7 games are played and the winner is whoever wins more of the allotment of games.
In some sports (or “games” if you want to gatekeep what a sport is), series can go even longer. In professional snooker, some tournaments are best of as many as 35 games. The world chess championship is a best of 14 games.
Typically, it is features of the specific game that lead to how long a series is (how long and taxing games are, for example). But the best-of-X determination has huge impacts on who wins the series.
BYEs
Above, we talked about how bigger tournament de-emphasize the regular season bye giving more teams a chance. One way to counteract this effect while still allowing for big tournaments is a BYE week for the best teams.
In tournaments that have BYEs, the top few teams get an automatic win in the first round or two. This is typically a reward for performing well in the regular season and makes it so they have to play fewer teams to win the championship.
The NFL playoffs feature a BYE week for the top few teams, allowing them to avoid wild card weekend.The new college football playoff format for 2024 will feature BYE weeks for the top 4 teams in order to reward them for having particularly good regular seasons.
There is some thought by fans that BYE weeks may actually be detrimental. Is it bad for your team to not play for a longer period of time? Do they get rusty by not playing? Would it be better if they had played to begin with? This website studied the BYE week effect and determined that this hypothesis holds no water. At the end of the day BYE weeks just give you a free pass to the next round.
Other Concepts
There are some other fun features that different playoff formats might have. The most common type of tournament is a bracket like in March Madness where you have to work your way all the way through to win. We want to talk about three more tournament features which are a variation of this simple bracket: reseeding, round robins, and double elimination
Reseeding is something that shows up in a lot of professional tournaments like the NBA and NFL. A tournament has reseeding if “who plays who” isn’t determined until the later rounds are set.The idea is to let the strongest teams remaining get an advantage by playing the weakest teams remaining. An example of a tournament without reseeding is March Madness.
Round robin tournaments involve a component of group play before the traditional bracket starts. The idea is that you play every other team in your group and the teams that do the best move on. This shows up in the soccer world cup and in the new NBA in-season tournament.
Finally, some tournaments use the concept of double elimination. These tournaments work exactly like regular tournaments except you have to lose twice before you’re out. If you lose once, you enter the losers bracket. Eventually we’ll be left with one team that has not lost and the winner of the losers bracket (who has one loss). Typically the undefeated team has two chances to beat the winner of the loser’s bracket. A common example of double elimination tournaments is the college baseball playoffs.
How Playoff Format Impacts Who Wins
We’ve talked about different attributes a tournament can have, but what do they mean for how the tournament plays out? Some attributes are good for favorites, some for underdogs. The table below summarizes which attributes are good for who in different sports playoff formats!
Feature | Favorites | Underdogs |
|---|---|---|
Bigger Tournaments | – | + |
Longer Series | + | – |
BYE Weeks | + | No effect |
Reseeding | + | – |
Round Robins | + | – |
Double Elimination | + | – |
Let’s go through each of these to explain how the table above came to be.
Bigger Tournaments
First, bigger tournaments are obviously bad for the favorite and good for the underdogs. Bigger tournaments mean more wins required for a championship. This also means more chances to get upset. Just look at the March Madness tournament every year. Even though the best teams get to play some pretty paltry opponents, they still lose quite often. This makes March Madness a tournament that the favorite actually rarely win.
Longer Series
The second attribute is how long a series lasts. The longer the series, the more likely it is for the favorite to win. You can kind of see this as “it is easy to upset a favorite once, it is harder to do it multiple times”.
The graphic below shows how the probability the favorite wins grows as the series goes longer. The labels in the legend refer to the probability the favorite wins any individual game in a series.
Note that for series that are evenly matched (the blue line, the favorite wins 50% of the time), the length of the series doesn’t help.
However, for mild favorites (who win 60% of individual games, the orange line), the probability of winning the series increases slowly as the length of the series grows.
For heavy favorites, (who win 80% of individual games, the green line), the probability of winning the series rapidly approaches 1 as the length goes on.
BYE Weeks
This one is easy. BYE weeks favor the favorites but don’t really affect the underdogs.
For the favorites, they have to win fewer games than they would otherwise due to the BYE weeks. Even if you’re a heavy favorite, there is still always a remote chance of losing in an early round against a huge underdog. This happens all the time in March Madness.
For the underdogs, it doesn’t really matter. They still have to win the same number of games to win the tournament whether or not the best teams get BYEs. They will still have to beat the best teams to win the tournament even if there are BYEs.
Reseeding
Reseeding helps the favorites and hurts the underdogs. When a tournament is reseeded, it means that the favorites get the easiest possible matchup in every round. It also means that the underdogs get the hardest possible matchup in every round.
Think of it like strength of schedule. Reseeding means the best teams get the easiest strength of schedule while the worst teams get the hardest strength of schedule. Who do you think will win the most games? That’s right, the favorites.
Round Robins
This one was hard to determine who it helped and who it hurt. Here is how we landed where we did. Consider a tournament that only had a round robin portion and whoever won the most games wins the tournament.
Just like in the previous section where longer series helped the favorites, more games being played here helps the favorites. The law of large numbers will take over and the best teams will tend to do pretty well in the round robin portion. It is harder for an underdog to rattle off multiple wins than it is for them to win one fluke.
For this reason, we claim round robin tournaments help the favorites and hurt the underdogs.
Double Elimination
Double elimination tournaments also help the favorites and hurt the underdogs. The reason is the exact same as why longer series and round robins help the favorites. If you have a “one and done” tournament, it is easy for a fluke to nip a favorite in the bud. However, playoff formats which feature double elimination give the favorites a cushion. It’s harder for lightning to strike twice.
2024 College Football Playoff Format
With our new found knowledge about what playoff formats help or hurt favorites, we want to look at the new 2024 college football playoff format.
The main changes with the 2024 college football playoff format is expanding the number of teams. In the BCS era, the playoff essentially consisted of 2 teams playing head-to-head in a single championship. This led to countless controversies and many claims of mythical national championships.
For the last 10 years or so, a four team playoff has been in place. The playoff committee tries to select the four best teams in a two round playoff to determine the championship. It worked well, but still led to controversies like the 2024 undefeated Florida St. team that got left out (and thoroughly beaten by Georgia).
For the 2024 college football playoff format, they’re moving to 12 teams to avoid this issue popping up again. How does this affect title probabilities?
On the surface, moving from 4 teams to 12 teams makes it harder for the champions to move. Using our table from above, this falls under the “bigger tournaments” row. However, there is a very interesting wrinkle in all this.
College football is pretty unique in one way. There are enough teams and few enough games played in a season that there are bound to be more than a handful of undefeated teams. It can be really hard to tell who the favorite is just by looking at records.
Even this year, Georgia was left out of the college football playoff because their resume was deemed worse than Alabama (who beat Georgia) and Texas (who beat Alabama). But there are lots of people that still think Georgia was the best team in college football this year. This was backed up convincingly when Georgia beat undefeated Florida St. by 60 in the Orange Bowl.
My point is this: on the surface moving from 4 to 12 teams might make it less likely for the best team to win. However, a four team playoff is not guaranteed to even have the best team in it (like, maybe, the 2023 season)! Because of this, moving from 4 to 12 might make it more likely the best team wins.
At the end of the day, tournament size is a tradeoff between giving a chance to everyone who deserves it while still rewarding those who performed well in the regular season. Clearly, in CFB 2 or 4 teams weren’t enough. Is a 12 team playoff the best choice for the 2024 college football playoff format? I personally think a 6 team playoff was the answer, but we will see.
