They are the men who start each game on the sidelines, but could be called upon at any moment. Their presence can change the course of a match, and with the reduction of the interchange next season they're about to become a whole lot more important.
NRL.com takes a closer look at the top 10 interchange weapons from the 2015 NRL Telstra Premiership.
10. Ben Hannant (Cowboys)
An off-season recruit from the Broncos, Hannant was always going to find it difficult starting ahead of North Queensland's representative props James Tamou and Matt Scott, but has offered plenty from the interchange and also done everything that's been asked of him when required to start. Looking very much like a man on a mission, Hannant has featured in every game for the Cowboys this season. Having last played in a grand final in 2006 with the Broncos, 2015 could be Hannant's second crack at the game's biggest prize.
9. Chris Grevsmuhl (Rabbitohs)
Following the departure of Sam Burgess and Ben Te'o, there were opportunities for other players to force their way into the South Sydney 17 in 2015. After a season with the Rabbitohs' feeder club North Sydney in the NSW Cup, Grevsmuhl made his NRL debut in Round 1 this year on the back of an impressive pre-season which included success with the Indigenous All Stars as well as Auckland Nines and World Club Challenge victories. Grevsmuhl has been a regular on the South Sydney bench since, scoring five tries so far in his rookie season.
8. Ben Barba (Sharks)
Initially brought to the club to partner Jeff Robson in the halves, the emergence of Jack Bird saw Barba move between the bench and fullback for a six-week period, before coach Shane Flanagan finally settled on an interchange spot with Barba playing a role reminiscent of his early days at the Bulldogs under coach Kevin Moore. The circumstances of each game tend to dictate Barba's involvement, often coming on to play fullback with Michael Gordon shifting to the wing if there are no other injuries. With the Sharks bound for the finals, the returning Barba could be the x-factor that helps the Sharks to their maiden premiership.
7. Shannon Boyd (Raiders)
This Raiders prop doesn't mess around, getting through plenty of work as his minutes have steadily increased this season. Has crossed for five tries, including a double against the Tigers in Round 22, and has taken on more responsibility following the departure of fellow prop Dane Tilse.
6. Kane Evans (Roosters)
Part of the Roosters system for a number of years, Evans has really started to come into his own in 2015. The loss of Jared Waerea-Hargreaves to a season-ending knee injury meant fellow props Sam Moa and Dylan Napa locked down starting berths, with Evans now playing closer to 40 minutes each week.
5. Jack de Belin (Dragons)
One of St George Illawarra's quiet achievers, de Belin has stepped up to become an integral part of the Red V engine room. With 26 offloads for the season and an average of 35.2 tackles and 121.3 metres per game, de Belin is a strong candidate to move into the starting side on a more permanent basis next season. Showing his versatility, the middle forward spent two games this year at halfback in the absence of Benji Marshall.
4. Paul Vaughan (Raiders)
One of Canberra's two interchange colossuses, Vaughan has been racking up some impressive totals, with 3244 running metres at an average of 141 metres per game. That ranks him at ninth in the league for that stat, the best of any Raiders player. Has also conceded just two penalties all season in 23 games to date, a sign of good discipline in the middle of the park.
3. Trent Merrin (Dragons)
The NSW forward has switched between starting and an interchange role all season, but some of his best work came when he started on the pine in a similar role to which he plays for the Blues. Merrin averages a huge 156.4 running metres and 33.9 tackles per game, but also has been used as a decoy on 122 occasions, ranked 15th in the league for this stat in 2015. He may move into the starting side on a regular basis at new club Penrith next season.
2. David Klemmer (Bulldogs)
2015 marked a breakout year for the 197cm prop, who made his mark in the Origin arena at just 21. He's perhaps the ultimate interchange player, given he started a game for the first time in Round 9 this season after making his debut back in Round 1, 2013, and has only started in a total of four games since. Averages 148.8 metres and 22.5 tackles per game, and could well be a mainstay for the Bulldogs, NSW and Australia in the coming years.
1. Sio Siua Taukeiaho (Roosters)
Named on the bench to little fanfare in the Roosters' Round 1 victory over the Cowboys, Taukeiaho featured in short bursts for the first few weeks of the competition. But his performances began to warrant a larger role, with his minutes gradually increasing before being named in the starting 13 against the Storm in Round 7. Of regular NRL forwards, only Cowboys wrecking ball Jason Taumalolo makes more metres per run than Taukeiaho. Averaging 118 metres per game and with 44 tackle breaks for the season, his relentless efforts both in attack and defence have seen Taukeiaho become a key part of Trent Robinson's title-challenging side.
This article first appeared on NRL.com