Only to him, it's not called the 15. It's the flat route-corner route.
That's what happens when you're a quarterback so steeped in a numeric-based offense, you know it like your mother tongue.
" Cam Cameron used to tell me that when I first got here," Rivers said of the former Chargers offensive coordinator. "He'd say, 'If you drive down the highway and see whatever, Highway 78, if you don't think of the route combination 78, then you're crazy.'
Rivers leads the NFL in yards passing (3,177), yards per completion (9.0), touchdown passes (23), and completions of more than 20 yards (50) and 40 yards (12). He's a big reason the Chargers also lead the league in total offense at an average of 418.2 yards, almost 20 yards more than second-ranked Philadelphia.
A lot of that is skill and teamwork, of course, but it's also the familiarity and comfort Rivers has with the system, one that has allowed the Chargers to remain productive despite their revolving door of receivers.
"Philip's very good at seeing the field," said Chargers quarterbacks coach John Ramsdell, who worked in the same capacity with Kurt Warner in St. Louis. "He sees everything. Not every quarterback does that. Kurt did it. They can process everything, see it all. The game's like in slow motion."
Rivers said he and his receivers are so in tune, it's as if they share the same mind.
"That's when it's fun," he said, "when you can look at a guy who's 30 yards away from you on the practice field, and it can be a very subtle head nod or hand signal, and it's like we could have just talked for five minutes about that play: 'Yeah, I got ya. That's what I thought too.'
"It's just from studying together and watching. We can get a lot said in about two seconds."
That's not just with the receivers and backs. Rivers is similarly in sync with his offensive linemen.
"There's times I tell them in the huddle, probably a couple times a game, 'Hey, I need a little extra here.' I tell them before I call a play. They kid me afterward like [sarcastically], 'Oh, great. We love it when you tell us that.' But it's just like, 'Hang on, because we've got a chance for something big.' "
Just as Rivers thinks in numbers, so do the players around him. Pro Bowl receiver Jackson, who makes his return Sunday night at Indianapolis after missing the bulk of the season as a contract holdout, said he makes the playbook association whenever he sees a familiar number on TV, in a movie, or even on his cellphone.
"If somebody calls from a phone number that starts 585, well, 585 is one of our routes," Jackson said. "It's a base route for us. I'm an outside receiver, I have the 5 — the last digit — and 5s are 18-yard comebacks. That's a staple in this West Coast offense."
To Jackson, the most meaningful of those three-number combinations is 678, which is a corner route by Gates, and an 8-route, a post over the top to occupy the safety. At least 90% of the time, that pass is going to Gates. But every so often, if the safety decides to cut down and cover the tight end, the 6-foot-5 Jackson just might get a chance for a deep ball with single coverage.
It was that play — 678 — that clinched the victory for the Chargers on a rainy Christmas Eve in Seattle in 2006, when Jackson caught a 37-yard touchdown pass with 29 seconds left for a 20-17 victory.
"When I hear 678, it's Christmas Eve in Seattle," Jackson said.
That number also conjures memories for Gates — too many to count.
"The actual 7-route itself established me as a player when I came into this league," said Gates, an All-Pro. "I've got a homeboy in Georgia who calls me from the 678 area code, so my mind goes to that play every time it comes up on my phone."
For receiver Malcom Floyd, the higher his number, the better.
"I like the 9s," he said. "That's a bomb, and I like the deep ball. That's the number that will ring a bell."
For Rivers, that's all an indication of an offense being on the same page, where players aren't just clocking out and leaving their job at team headquarters, but living it.
"You're driving down the road and you see the slants, the comebacks, the curls," he said. "It's silly, but it's cool."