The 'spine' is often an indicator of the strength of an NRL team, so ESPN has analysed the best 1, 6, 7, 9 combinations and reveals which clubs will show a little backbone in 2017. How does your club rate?

1. Melbourne Storm (Billy Slater, Cameron Munster, Cooper Cronk, Cameron Smith)

The Storm appear to have invested about 80 percent of their salary cap in their spine, and it should be money well spent.

Some doubt remains about Billy Slater's future, but Melbourne, if he is fit to play, will arguably have three future immortals and a potential Kangaroos representative making up the best spine in the NRL.

2. New Zealand Warriors (Roger Tuivasa-Sheck, Kieran Foran, Shaun Johnson, Issac Luke)

Through good luck or good management, the Warriors boast the best New Zealand international spine; but there are hurdles to clear before they can see them all on the park together.

Kieran Foran's personal problems are well documented, and the former Manly and Parramatta star is still awaiting clearance from the NRL before he can return to the field. Speculation is building that he won't be given the green light before round one.

3. North Queensland Cowboys (Lachlan Coote, Michael Morgan, Johnathan Thurston, Jake Granville)

A tried-and-true combination as evidenced when they joined forces to win the 2015 NRL premiership. They are all another couple of years older but the Cowboys are blessed to have arguably the greatest player in the history of rugby league pulling the strings.

The Cowboys' spine may not have the glamour or the price-tag of the top two in our rankings, but they do have the runs on the board and their proven combination will ensure they are in good hands in 2017.

Johnathan Thurston and Michael Morgan have struck a formidable halves combination for the Cowboys. Photo by Mark Metcalfe/Getty Images

4. South Sydney Rabbitohs (Greg Inglis, Cody Walker, Adam Reynolds, Robbie Farah)

Any spine that features Greg Inglis is strong, but the addition of Robbie Farah in 2017 has improved Souths' immeasurably.

Adam Reynolds was also a standout in a disappointing 2016 for the Rabbitohs, as evidenced by his emergence into the New South Wales State of Origin team, and the fine form of Cody Walker at the back end of the campaign suggests the Bunnies could potentially have one of the most potent spines in the NRL.

5. Penrith Panthers (Matt Moylan, Te Maire Martin, Nathan Cleary, Peter Wallace)

The Panthers have the best young spine in the NRL, featuring players who are fantastic in their own right and, with the exception of veteran hooker Peter Wallace, have endless scope for improvement.

Te Maire Martin and Nathan Cleary are two of the NRL's brightest young stars who could figure prominently in representative football this year; add their youthful exuberance with the experience of Matt Moylan and Wallace and Penrith have the nucleus of a genuine premiership contender.

6. Brisbane Broncos (Darius Boyd, Anthony Milford, Ben Hunt, Andrew McCullough)

The Broncos' spine is strong on paper but 2016 probably saw them slip in the rankings: Darius Boyd remains one of the NRL's marquee players, but Anthony Milford, Ben Hunt and Andrew McCullough struggled to carry their sizzling 2015 form into last season.

(There has been speculation about the future of Hunt at Red Hill and unless sorted one way or the other soon it has the potential to disrupt the 2017 campaign but the Broncos need him, Milford and McCullough to return to their best form in order to give the premiership a shake.)

7. Manly-Warringah Sea Eagles (Tom Trbojevic, Blake Green, Daly Cherry-Evans, Api Koroisau)

The addition of former Storm five-eighth Blake Green suddenly has the Sea Eagles' spine looking a lot more impressive than it did in 2016, and his arrival will benefit Manly in more ways than one.

Green will take a great deal of pressure off Daly Cherry-Evans while also allowing makeshift pivot Dylan Walker to push wider to his favoured position of centre, where he will be a lot more dangerous. Add the incredible talent of Tom Trbojevic at fullback and a premiership winner in Api Koroisau at hooker, and Manly have one of the better spines in the NRL.

Mitchell Pearce and Jake Friend will be key figures in the Roosters spine that will include former Rabbitoh Luke Keary in 2017. Photo by Ryan Pierse/Getty Images

8. Sydney Roosters (Latrell Mitchell, Luke Keary, Mitchell Pearce, Jake Friend)

Like Manly, the addition of a new five-eighth, in Luke Keary, has given the Roosters a much more potent look down their spine. Keary is a proven competitor who has also tasted premiership success; he plays a similar game to James Maloney, who has been a major loss for the Tricolours.

Mitchell Pearce will be highly motivated to return to rep football, after his off-field issues at the start of 2016, and Jake Friend is within reach of Origin after selection in the successful Kangaroos Four Nations squad. Promising youngster Latrell Mitchell will be better in his second year in the NRL.

9. Wests Tigers (James Tedesco, Mitchell Moses, Luke Brooks, Matt Ballin)

The Tigers' spine is fantastic on paper but there are plenty of question marks. Like the Panthers, they have a wonderful mix of youth with James Tedesco, Mitchell Moses and Luke Brooks along with the experience of two-time premiership winner Matt Ballin.

BUT... there is some uncertainty about Ballin who, at 33-years-old, will return from two knee reconstructions. They will also have the distraction of contract negotiations with their big four; Tedesco, Moses, Brooks and Kangaroos' prop Aaron Woods are all free agents at the end of 2017, and the vultures are already circling.

The Tigers may have to deal with the probability of one or more leaving, and the Robbie Farah saga proved the fans aren't afraid to make their feelings known when a club favourite is forced away from Leichhardt.

10. Canberra Raiders (Jack Wighton, Blake Austin, Aidan Sezer, Josh Hodgson)

The Raiders were one of the surprise packets in 2016, and their spine was one of the reasons why. But can they repeat, or even improve on, last year's form?

The Raiders don't boast a significant amount of representative football in their spine, with the exception of Josh Hodgson, which means there is a doubt they can repeat their scintillating form of last season in 2017. That is not to say they can't, but there is a doubt.

James Maloney and Chad Townsend guided the Sharks to the 2016 NRL premiership but how will they go without the retired Michael Ennis? Photo by Cameron Spencer/Getty Images

11. Cronulla-Sutherland Sharks (Valentine Holmes, James Maloney, Chad Townsend, Jayden Brailey)

The premiers will enter their title defence with a slightly different spine to that which won Cronulla their maiden premiership in last year's NRL Grand Final, and one change in particular could be more significant than the club or its fans realise.

Ben Barba will be missed after signing for Toulon to play rugby union in order to escape 12-match ban imposed by Australia's NRL after he tested positive for cocaine while celebrating the Sharks' premiership success, but the biggest challenge facing Cronulla is: Can they fill the void left by the retirement of hooker Michael Ennis? Ennis' absence significantly weakens the look of their spine, and the impact he had on Cronulla's premiership glory will only be felt when the competition starts.

12. Gold Coast Titans (Jarryd Hayne, Ash Taylor, Kane Elgey, Nathan Peats)

A very tidy looking spine with last year's late and unexpected additions of Jarryd Hayne and Nathan Peats adding some polish, but there are some question marks in the halves.

Ash Taylor was sensational last year in claiming the Dally M Rookie of the Year award, but he now faces the challenge of taming the dreaded "second-year syndrome" while Kane Elgey missed last season with a knee reconstruction.

13. Canterbury Bankstown Bulldogs (Will Hopoate, Josh Reynolds, Moses Mbye, Michael Lichaa)

The Bulldogs' spine, like their entire team, is unpredictable: When they're on, they are world beaters; but when they are off, they might battle to compete with the under-17 team from their local club the Chester Hill Hornets.

The spine looks solid on paper but in reality it falls short of expectation and the quartet must step up a level or two in 2017 if the Bulldogs are to calm their growing number of disgruntled fans and climb up the NRL ladder into the top four; if they don't, heads may roll -- on and off the field.

14. Parramatta Eels (Bevan French, Clinton Gutherson, Corey Norman, Isaac de Gois)

Parramatta have highly talented players in their spine but two are playing out of position. Bevan French gave NRL fans a taste of his freakish ability at the end of 2016, with 19 tries in 13 matches, so 2017 looms as exciting on that front for the long-suffering Eels faithful.

Clint Gutherson and Corey Norman are excellent players in their own right, but both will likely be playing out of their more accustomed positions. Gutherson has played most of his football as a fullback, winger or centre, and his brief cameo filling in at five-eighth last season was good without being brilliant. Corey Norman is a five-eighth not a halfback, but he will wear the No. 7 jersey due to lack of options, while Isaac de Gois is crafty but past his best and on the wrong side of 30.

The Eels spine looks strong but a lot will depend on how Clinton Gutherson adapts to a relatively new position at five-eighth. Photo by Mark Nolan/Getty Images

15. St George Illawarra Dragons (Josh Dugan, Gareth Widdop, Josh McCrone, Cameron McInnes)

With the exception of Josh Dugan, the Dragons appear to be severely lacking in quality in their spine. Gareth Widdop in 2016 was a shadow of the player he once was, and the season-ending injury to young halfback Drew Hutchison has left them to rely on journeyman Josh McCrone in the No. 7 jumper.

Former Souths hooker Cameron McInnes is a solid addition but not the type of player who will make the level of difference needed desperately by the Dragons. Even more alarming for fans of the Red V fans: there isn't much depth in these positions within the club so it might be another long and painful year ahead in 2017.

16. Newcastle Knights (Dane Gagai, Brock Lamb, Trent Hodkinson, Rory Kostjayson)

The Knights have a similar story to the Dragons in that they have a very talented fullback in Dane Gagai but the more you look the more concerned Newcastle's fans should be. Jarrod Mullen and Trent Hodkinson have been quality players throughout their careers but those days are long gone and both have been hampered by a variety of injuries over recent seasons.

Former Cowboys and Storm utility Rory Kostjayson is a neat piece of business, and he will bring some much-needed experience to the young Knights squad, but he will receive a ride shock going from two highly successful clubs in North Queensland and Melbourne to cellar-dwellers who face another long season short on highlights.