When Carson Wentz, Zach Ertz and their Eagles teammates take the field Sunday in the Superdome in New Orleans, they'll be sporting their midnight green home jerseys. Yeah, that's unusual. But there's a good reason: Thank Doug Pederson.

As we reported in July, the Eagles coach and his Saints counterpart, Sean Payton, golfed together at the NFL's annual meeting in Orlando in March. They put a little bet on the match, with jersey colors at stake. Pederson won his hole. The Eagles would wear green.

"We've got to play for something, and let's do something and we started talking about it. And we started talking about jersey colors," Pederson said on a conference call in July. "I remember Sean saying there's only so many things as head coaches we can control. And obviously we can control this. And I said, you know what? This is a great idea. … I was fortunate enough to win that bet."

The Saints will be wearing all white — their color-rush jerseys, in fact — which are popular among fans in Louisiana.

Seeing the Eagles in green on the road is fun, but plenty of readers would rather see the Eagles in a different type: kelly, of course.

In fact, we had one reader pose the question to us through Curious Philly, our tool that lets readers ask our journalists about the city — its people, its teams, the things that make it unique.

The reader notes that the Eagles have said before that they can't wear the throwback uniforms because of an NFL rule. But they bring up a good point: How come teams such as the Rams and the Giants can get away with it? Well, it all comes down to style (and safety).

Jared Goff and the Rams wore their throwbacks this past weekend.
Mark J. Terrill / AP
Jared Goff and the Rams wore their throwbacks this past weekend.

The NFL has specific rules about how often a team can switch helmets during a season. A recommendation was made to the NFL in 2013 that suggested teams limit the amount of time they wear new helmets, according to uni-watch.com, because helmets are less safe when they're new. They need to be broken in. (Uni-watch points out that does seem counterintuitive, but that's what the science says.)

The league says each team can have only one helmet "shell," which is why the Eagles can't wear kelly green throwbacks. Their shell, in midnight green, wouldn't pair well with the jersey.

Teams can change face masks and decals, but can't change the color. (No, you can't paint it — it would take too long to dry. No, a vinyl wrap doesn't work, according to Uni-watch — that would be a safety risk.) So when you saw the Giants in throwbacks during their Week 6 matchup with the Eagles, they weren't wearing new helmets. They were wearing their regular ones, which are the same color needed for their throwback uniforms.

And when you see the Rams swap out their white horns for yellow, it's the same thing — the shell doesn't change, just the face mask and the decals.

Know that Eagles owner Jeffrey Lurie is fighting for you, fans. He said last season he was pushing for the NFL to change the rule.

" I would love to see it," Lurie said in March 2017. "I love the midnight green; I think it's great. But I also want the kelly green. I'd love for us to have both and some games have one and some games have the other. I think that would be more fun."

Chuck Bednarik and his 1960’s teammates wore the kelly green during a ceremony prior to the Eagles’ season opener in 2010.
MEL EVANS / AP
Chuck Bednarik and his 1960’s teammates wore the kelly green during a ceremony prior to the Eagles’ season opener in 2010.