It has become so elusive, almost to the point of taking on mythical qualities.
Sure, the single-season NFL record that Dan Marino set by throwing for 5,084 yards in 1984 is breakable. Like any offensive mark, it is ripe to be broken if only because of the league's efforts, through changes in rules and enforcement, to give passers and receivers optimum freedom to operate.
But when is someone going to actually break it? In 26 years, multiple quarterbacks have been on "Marino's record pace," only to eventually fall off and fall short.
Rivers chasing Marino
Perhaps this season will be different. Perhaps Philip Rivers will be the one to finally go the distance and supplant Marino in that cherished spot in league history.
Through nine games, the San Diego Chargers' quarterback has thrown for 2,944 yards. That projects to 5,234 yards for a 16-game season, which wouldn't just break the record. It would obliterate it.
However, that isn't the only reason to like Rivers' chances. Here are more:
» He has put up remarkable numbers despite being without his number one receiver, Vincent Jackson, who hasn't played because of a contractual holdout and three-game suspension after he rejoined the club that will keep him sidelined through Week 11. Rivers' other top wideouts, Malcom Floyd and Legedu Naanee, have missed three and four games, respectively, with hamstring injuries. And Rivers' favorite target, tight end Antonio Gates, has missed a game and continues to be hobbled by a torn plantar fascia in his right foot.
» A strong case can be made that Rivers will become even more prolific through the final seven weeks of the season. For one thing, Floyd and Naanee are expected to return to the lineup for Monday night's AFC West showdown against the Denver Broncos, although Gates' status is up in the air. For another, Jackson's due to make his season debut in Week 12 against the Indianapolis Colts.
» The Chargers' shaky running game, which ranks 16th in the NFL, makes it natural for them to rely more heavily on the pass.
» The Chargers are 4-5, and it is likely that Rivers and his teammates will need to go full throttle if they are to have any chance of winning a fifth consecutive AFC West title or making the playoffs. The Broncos' game is the first of four against divisional opponents through the balance of the schedule.
After eight games, Rivers had 2,649, which broke the NFL mark for that period, which Fouts had set in 1982 with 2,580.
Fouts sees many reasons why Rivers has been as dominant a passer as Fouts once was. The biggest is the same reason that Fouts credits for most of the crazy passing stats he was able to generate: His relationship with his head coach.
Fouts had the late Don Coryell, whose legendary "Air Coryell" attack allowed his quarterback to generally seek to throw for touchdowns before first downs. Rivers has Norv Turner, who learned most of what he knows about offensive football from the Coryell coaching tree by working with former long-time Coryell assistant coach Ernie Zampese.
"I think the relationship (Rivers) has with Norv is as good as it gets," Fouts said. "And I think that's the key because Norv is having to really get creative and use a lot of guys that nobody has heard of. But the system -- and it all goes back to the 'Air Coryell' stuff -- is so easy to pick up for that guy, in a couple of practices, a quarterback can feel comfortable knowing (his receivers) will be in the right spot."
Turner appreciates his quarterback's record pace. But like Rivers, he is far more focused on how the production translates to success on the field. Turner is thankful that Rivers has been able to not only overcome the absences of some key weapons, but also bail out a team that has frequently self-destructed, primarily from poor play on special teams.
In addition, the coach doesn't see Rivers' lofty midseason production, despite all of the attention it has generated, as anything new.
"This is the fourth year he's been playing at this level," Turner said. "You look at the seasons before this, two straight 4,000-yard seasons and right around 30 touchdown passes and 13 wins a year ago, he's played at an awfully high level for four years. I think people are taking notice because of the yards, and it's unfortunate because we'd like the (won-loss) record to be better and that's what our prime interest is over the next seven games."
Turner cites several reasons for Rivers having what could very well prove to be the best of his seven NFL seasons.
"Growing as a player and being in the same system and being with the same players over an extended period of time, that's where you get the kind of performances that Philip's had and you get a consistency he's had," the coach said. "He's worked awfully hard in terms of his strength and his conditioning and his athleticism and all those things. He's come a long ways since probably he was a young player.
"There are a lot of guys who can make a lot of the throws that all of these guys that play in the NFL make, and then there are certain guys who can make certain throws. And he's one of those certain guys. He looks to fit the ball in when some other guys maybe are not trying to throw it and he'll make the tough throws in the most critical situations where some other guys may not be capable of making that play."
Fouts' broadcast assignments for CBS have caused him to pay particularly close attention to Rivers. He believes Rivers' makeup, physically and mentally, allows him to consistently succeed as a long-ball thrower.
And that, of course, is a trait near and dear to Fouts' heart.
"He can reach every part of the field," Fouts said. "And he doesn't under-throw guys. You see a lot of guys that are out there and they under-throw the bomb, and you get a pass interference or the defensive back will break it up. But Philip is always looking to lead the guy and, for a receiver, that's what they want. They want to be able to go get it. They don't want to have to come back and out-jump somebody.
"He understands the pocket, he understands protection. And he understands that the calm in that hurricane is right in the middle of the pocket, the eye of the storm, if you will. A lot of guys aren't comfortable with all that swirling around him, but he steps into that eye, and it may be shrinking all around him, but he's oblivious to it. Guys are hanging on him and he's still throwing the ball and he's still throwing it accurately."
When the storm settles at the end of the season, Rivers and the Chargers hope they'll be celebrating another division crown, or at least a wild-card berth.
As a bonus, Rivers could also own one of the more elusive records in the NFL.