If you like football and you like video games, you must certainly be aware of the “Madden Curse.” Each year, EA Sports releases a new version of Madden, a video game based on the National Football League. Each version of Madden features a different NFL player on the cover of the game. And it seems that each year, the player featured on the cover gets hurt or has a terrible season. Thus, the “Madden Curse” was born.

As a statistician, I’m always skeptical of these things. When people make judgments based on their own perception and not on data, it can be easy to think you see trends that aren’t really there. We tend to remember the cases that support our point of view (Michael Vick breaking his leg after being on the cover) and forget cases that don’t support our argument (Calvin Johnson setting the single season receiving record after being on the cover).

But I’ll humor the Madden curse theorists and perform a data analysis to see if a curse might indeed be real. And if it does exist, perhaps we can even figure out why!

# Are Madden-Featured Players Getting Hurt More Often?

We already mentioned that Michael Vick broke his leg the season after he appeared on the cover of Madden. He missed 11 regular season games that year. So could be the curse be that the featured players get injured and miss a lot of games the next season?

For all 16 players who have been on the cover since 1999, I gathered the number of games they played the season before being on the cover, and the number of games they played after. You can follow along by getting the data here. Don't already have Minitab?  You can get a 30-day trial version.

First, I ran a Paired t-test on the two groups.

We see that on average, players played about 2 fewer games the season after being on the cover for Madden. This difference is statistically significant at the α = 0.10 level. So is the curse true?

# Statistically Significant and Practically Significant

Just because a difference is significant doesn’t mean that difference is practical to your situation. So when it comes to the Madden curse, we have to ask ourselves “Is a difference of 2 games really a curse?” Sure, Vick’s injury was bad, but it wasn’t typical. The only other players besides Vick to play in fewer than 10 games after being on the cover were Troy Polamalu (5 games in 2009) and Donovan McNabb (9 games in 2004). On the flip side, 10 of the 16 featured players played in at least 14 games the next season. That doesn’t sound like much of a curse to me.

And keep in mind that EA is not going to put anybody on the cover of Madden who was injured the previous season. The outliers of Vick, McNabb, and Polamalu pull down the average of the entire “appeared-on-the-cover” group. That doesn’t happen the season before you’re on the cover. Fifteen players played in at least 13 games the season before being on the cover, and 10 of them played all 16. This means the “before” group is artificially inflated.

So yes, players are playing fewer games the season after being on the cover. But on average, it’s only 2 fewer games. Featured players aren’t experiencing season-ending injuries year after year. When you consider the practical difference, I would say 2 games is so small that there isn’t any curse going on.

# Are Players Performing Poorly?

So if injuries don’t appear to be the curse, maybe players have a worse season the year after being on the cover. Assessing this becomes a little tricky because the players on the cover play a variety of positions, including two defensive players. So we need a statistic that can represent the value of players at different positions. Pro-Football-Reference has a statistic called Approximate Value (AV). It’s a metric that puts a single numerical value on any player’s season, at any position, from any year. I know it’s not well known, but I’m not aware of any other statistic that can represent the value of Ray Lewis, Eddie George, and Michael Vick. For our purposes, it’ll do just fine.

I took each player's AV the season before they were on the cover and the season after. Then I did another paired t-test.

There is a difference of almost 5, and this difference is statistically significant since the p-value is less than 0.05. To give you some perspective on AV, during his record -setting year in 2012, Calvin Johnson had an AV of 14. So the average of 15 that the “Before” group has is pretty darned good (in 2007 Tom Brady had a 24, so I'm guessing that's about the max). In comparison, Bills receiver Steve Johnson had a 9 last year, and 49ers receiver Michael Crabtree had a 10. I think it’s safe to say a difference between 10 and 15 is practically significant.

This means there is a curse! Players on the cover of Madden perform worse the season after being on the cover. There is proof that the curse exists!

Or is there?

Let’s look at how players perform two seasons before they are on the cover of Madden. We’ll compare that to how they perform the season after being on the cover.

There is pretty much no difference in a player’s performance two seasons before being on the cover, and the season after being on the cover.

Okay, what if we go back three years before they were on the cover?

(If you've noticed the different sample sizes in these paired t-tests, it’s because a few of the players were so young that were not even in the NFL 2 or 3 seasons before being on the cover of Madden.)

Almost the exact same thing! There is really no difference in a player’s performance 3 seasons before being on the cover, and the season after. The only season that stands out is the one directly before they were chosen to be on the cover of Madden.

Now the curse makes sense. It’s a simple case of regression to the mean!

# What Is Regression to the Mean?

Think of a roulette wheel where half of the spaces are black, and the other half are red. And now imagine a set of 16 spins where red comes up 75% of the time. In the next set of 16 spins, we would expect the average to regress back to 50% red and 50% black. This is regression to the mean.

Note that regression to the mean does not mean we would expect a set of 16 spins where we had 75% black to “even out” the previous set that had more red. We would just expect the results to return to the average, which is 8 red and 8 black.

Now let’s apply this thinking to the Madden curse. We see that 3 seasons before being on the cover, the players as a group have an AV of about 11. It stays in the 10-11 range the next season, too. Then all of the sudden it jumps up to almost 15 the season before they make the Madden cover, only to return back to the “average” the following season.

It doesn’t take a Six Sigma Black Belt to see what is going on here.

Madden is selecting players who had outstanding seasons the previous year. But just like a roulette wheel might have a run where it comes up red 75% of the time, the outstanding performance by the players who appear on the cover is not sustainable. So the year after they're featured they don’t perform as well as they did the year before, and it looks like they’re cursed. In reality, they’re simply playing back at the same level they were before their outstanding season. They’re just regressing to the mean, and it would have happened whether they appeared on the cover of Madden or not.

So before you start believing in curses, try a statistical analysis first. Odds are you’ll find a perfectly reasonable explanation!