Often operating almost as an extra half-back, they have to possess creative powers and accuracy out wide as well as the more traditional defensive prerequisite.
A blend of not only the right skills but also temperament and fitness are needed and it has fast become one of the most influential positions in any squad.
That is one of the reasons, then, why Castleford Tigers head coach Daryl Powell made his move for Gareth O’Brien this week, the experienced England Knights full-back hoping to feature against champions St Helens tomorrow after joining on loan from Toronto Wolfpack.
With Jordan Rankin’s unexpected return to Australia during lockdown, Powell had tried winger Greg Eden in the No 1 role in their first game back in action against Catalans Dragons last Sunday.
Eden, of course, has played there previously, once famously described in his younger days by his then Huddersfield Giants coach Nathan Brown as “the next Billy Slater”.
However, for all his talent, it has been clear for some time that he is more suited out wide.
Powell had been thinking about making a bid for O’Brien when Toronto first hit problems last month but decided to first allow others at the club to stake their claim for the vacant spot.
But he revealed that it was directly after Sunday’s 40-14 defeat against the French side that he realised he needed a specialist in camp.
With O’Brien now on board at Wheldon Road, Powell has likened him to one of the club’s big fans’ favourites of the last decade – Luke Dorn.
As Powell started his rebuild of the club, the popular Australian – in his second spell there – scored 45 tries in 59 games between 2014 and his retirement in 2016.
Powell recalled: “The full-back who was outstanding for us a few years ago, Luke Dorn, had similar capabilities to Gareth. He played at half-back earlier in his career, really understood the game and was a good communicator and an instinctive reader of the game.
“I think Gareth O’Brien is exactly that – he can see things very quickly, his communication is great, he has got pace and his decision-making is excellent.
“All those things make for a good full-back; he reminds me a bit of Luke Dorn and what Dorny did for us was exceptional.”
O’Brien, who famously scored a Golden Point drop-goal for Salford that relegated Hull KR, did actually play two games on loan at Castleford in 2013 when he was starting out at Warrington Wolves.
Ironically, the same year he also featured on loan with tomorrow’s opponents Saints before really coming of age with the Red Devils.
“He played at Salford and I think in quite a few ways they are similar to us in the way they play,” added Powell.
“He is used to structure and getting on the end of things.
“I have watched him train and he looks fit, he gets round the field and understands the game.
“He can read where space is and where the ball needs to go, he is an experienced player and he has found it pretty easy.
“We have given him a fair bit of video work to do since he signed for us and he has looked comfortable, so, hopefully, if he does play he will handle it pretty well.”
Saints – whose England hooker James Roby is set for a 500th career appearance – were outstanding when vanquishing Leeds Rhinos 48-0 on Sunday.
That said, Castleford did beat them at Wheldon Road in their last outing before lockdown in March.
Powell said: “They are an outstanding team, full of quality players. They are a very difficult team to play against and they have come back (from the Covid-19 break) great.
“Leeds would say they weren’t at their best last week, but St Helens played really sharp, fast, direct rugby league.
“We feel we can do that; we will learn from last week and we will be a better team because of what happened to us.”
Castleford prop Liam Watts returns from injury for his 250th Super League game and ready to lock horns with Alex Walmsley, his England rival who was almost unplayable against Leeds.