The pair has connected on seven touchdowns in the last five games and four in the last two. It's not a coincidence that they seem to be getting more difficult to stop with each game that passes.
"I think in any relationship, whether it's a significant other or a teammate, the more time you get the better it always develops," Decker said. "I think the more we get on the same page, the more we understand nonverbal cues, certain routes and how to read defenses. All of those things, you can use to your advantage offensively. We're definitely clicking more as a unit offensively."
It starts on the practice fields, where Manning and his receivers use repetition to create chemistry and consistency. The pass-catchers learn exactly how Manning wants things done, and Manning learns how and where each receiver is most effective.
Even during training camp practices in the August afternoon heat, not a moment was wasted. While the coaches worked with the special teams units, Manning would grab a receiver or two and head to the opposite end zone to work on timing routes. Months later, it's paying off in big ways.
"I'd say (our chemistry) is a lot better than where it was Week 1," Decker said.
It might start on the practice fields, but it certainly doesn't end there. Part of what makes Manning so special - and what is making the Broncos offense something special - is the work put in when coaches aren't watching.
"When we have certain things we need to work on, Peyton grabs everybody and we all work on it together," Decker said. "We're finally in that groove and finding that it's paying off -- all the little details that always help you in big situations."
Opponents - such as Panthers Head Coach Ron Rivera - are taking notice.
"(Decker is) a smart football player and a football player that understands what Peyton is looking for," Rivera said. "I think any time you have that kind of rapport with a quarterback and a receiver, a quarterback and a (running) back, a quarterback and a tight end, you'll have success. I think that's what happened. They developed."
The communication has also improved, both in-game and in the film room. Decker said the way the offense communicates on the sidelines between drives has become more fluid and efficient. In the film room, the way the group analyzes game tape is a more collaborative effort.
With that comes a greater learning capacity, as all of the players on the offense can digest new information at a faster rate.
"The idea is being able to add more to your offense as the season progresses," Manning said. "'Hey, we can handle that. We can handle that change,' or that type of communication. You certainly want to prevent overloading guys and not letting them think too much. You want these guys to be able to play fast and play aggressive but the more games you play, the more experienced you should be and the better off you should be."
Four wins in the last five outings with an average of 31.6 points per game prove Manning's words to be true.
"We have a better understanding for one another," Decker said.
It's a relationship that, with a lot of time and effort, has come a long way since day one. While it might seem like they've reached their peak, there's still a long way to go before that happens.
"It takes a little while to get to know guys," Manning said. "I'm learning every week about my teammates and about myself in this new role. I think that's going to be ongoing the entire season. If you can have some success while you're learning, winning games, that's obviously a positive thing."