Back in the game's formative years the halfback and the five-eighth were the ones responsible for the attacking direction once the team set foot on the field, but in the past 30 years two other positions have come to the fore.
The introduction of the 10-metre rule expanded the influence of the hooker and in more recent times the fullback has evolved into someone not only expected to finish off attacking movements but to help create them.
Getting these four positions filled with quality players – and keeping them fit – is the aim of every NRL coach but NRL.com thinks these five teams have got the best mix for the modern game.
5. Roosters
They have a pair of halves both with Origin and grand final experience, an incoming fullback considered one of the most exciting prospects in the game today but unfortunately for the Roosters they will be without one of the best No.9s in the game for the first month or so of 2015. Jake Friend was forced to delay a full shoulder reconstruction due to a bacterial infection contracted from earlier surgery, forcing the Roosters to snare Matt McIlwrick from the Raiders as his early-season understudy. With a revitalised Mitchell Pearce, a five-eighth in James Maloney playing for a new contract and Roger Tuivasa-Sheck set to make Anthony Minichiello's jersey his own, the Roosters have the framework to once again challenge in 2015.
4. Panthers
In the past three years Matt Moylan has found himself stuck playing NSW Cup, Jamie Soward fell out of favour at the Dragons, James Segeyaro was stuck behind Aaron Payne at the Cowboys and Peter Wallace was doing his best to pilot a Brisbane team struggling to cope post-Locky. Now, this unlikely quartet have formed a combination that is equally balanced in game management and brilliance. In 2014 alone Moylan confirmed his status as a future superstar of the game, Segeyaro relegated Kevin Kingston to reserve grade and became an 80-minute player and Soward rediscovered the enthusiasm and energy that helped deliver him an Origin jersey and premiership in 2011. They are not an obvious star 'spine' but you'd imagine coach Ivan Cleary wouldn't swap any of them.
3. Rabbitohs
It took until Round 21 before South Sydney coach Michael Maguire sent out his team with the 'spine' he had envisioned all pre-season and when they took the field on seven occasions in 2014 they recorded six wins. Injuries to Luke Keary and Issac Luke early in the year put Maguire's plans on the back-burner but as they returned the Rabbitohs continued to build. With a spine of Inglis, Keary, Reynolds and Luke, the Rabbitohs defeated Manly twice, Canterbury, the Roosters, Broncos and Knights, Luke's grand final suspension preventing them from accumulating an 8-1 record. Inglis's transition into one of the game's elite fullbacks is now complete while the combination of Keary and Reynolds is capable of engineering many red-and-green victories in the coming years, if the club can keep them both.
2. Storm
The reference to a rugby league 'spine' may have had its foundations in Melbourne where Storm trio Cameron Smith, Cooper Cronk and Billy Slater have developed an innate understanding of each other's games over the past nine seasons. Intricately-planned ruck plays involving the 'big three' have been a feature of the Storm's early season wins in recent years but they will start 2015 minus arguably its most important cog. Smith's ankle surgery in December will likely see Ryan Hinchcliffe handed the hooker role early while the addition of five-eighth Blake Green to the roster is designed to ease the burden on Cronk. The Melbourne spine has needed little adjusting over the past decade but life without Cameron Smith is a daunting prospect.
1. Sea Eagles
Three Origin representatives and a an 18-time Test representative; it's little wonder we have chosen the Sea Eagles as having the most admired spine in the NRL. All told there are 30 Tests and 13 Origins between Brett Stewart, Kieran Foran, Daly Cherry-Evans and Matt Ballin, not to mention a Grand Final win in 2011 and a runner-up finish to the Roosters in 2013. In addition to his freakish try-scoring rate at Brookvale Oval, Stewart has become an accomplished provider of tries, complementing the attacking genius of Cherry-Evans and the uncompromising intent of Foran. Ballin is the relatively unheralded member of the quartet by everyone outside of Narrabeen but it's no coincidence that when he was missing at the end of last season, the Sea Eagles missed out on the minor premiership in Round 26 and fell out of the finals with consecutive losses to the Rabbitohs and Bulldogs. But when this spine is intact, there are none better in the NRL.
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