They get very little of the credit outside of the dressing room but premierships can't be won without them.

They are the unsung heroes that every team in the NRL possesses and former Sharks premiership winner Michael Ennis has highlighted those players he believe have critical roles to play for those teams still in finals contention.

Writing in the Round 21 issue of Big League, Ennis has named a player in each of the top nine teams that he says will have a major say in how the upcoming finals series plays out, even if they don't receive any of the headlines.

The likes of Andrew Fifita, Clive Churchill Medal winner Luke Lewis and Paul Gallen received many of the plaudits for Cronulla's drought-breaking grand final win but Ennis says there was one player in particular who didn't receive the credit he deserved, and this year's premiers will have players in a similar position.

"To win a premiership you need more than just the highest-paid players to be doing their job," Ennis says in Big League this week. 

"Who could forget Matt Prior's monumental finals series for Cronulla last season? Without his contribution, we don't win the grand final."

Two of Ennis's under-rated contributors go head to head on Friday night when the Broncos' Josh McGuire faces off against Parramatta lock forward Nathan Brown.

In different circumstances both players have come in to play a new role for their team and been a major factor in both sides sitting inside the top eight with six rounds left to play.

"I thought the Broncos would struggle without Corey Parker," Ennis admits, "but Josh has become a rock in the Broncos' pack and has added something more with his aggression and leg speed. 

"[Brown] is willing to roll the sleeves up, he's tough and under the coaching of Brad Arthur he's brought a nice short pass into his game."

Much has been made of the enormous losses of Johnathan Thurston and Matt Scott at the Cowboys this season but as the likes of Michael Morgan and Jason Taumalolo have had to accept more responsibility, Ennis pays special tribute to the contribution of front-rower Scott Bolton.

"Without Matt Scott, James Tamou and Ben Hannant up front, Scott Bolton has stood up and delivered," says Ennis.

"Jason Taumalolo, Gavin Cooper and Coen Hess steal the limelight, but Bolton has been the rock of the Cowboys pack."

The Cowboys meet the Roosters in Sydney on Saturday night with the Roosters out to record two wins on the trot for the first time since Round 14.

Like the Cowboys, the Roosters are battling on without two of their most experienced players in Jake Friend and Michael Gordon but it is second-year centre Joseph Manu who Ennis believes could prove to be a match-winner during finals time.

"The forward pack is so powerful and they lay a platform for their halves. But who do they play to?" Ennis asks.

"Joseph Manu is emerging as a real strike weapon for the Roosters."

The Round 21 issue of Big League features a cover story on Panthers half Nathan Cleary, Storm forward Tim Glasby remains focused on what made him a Queensland Origin player, the Eels prepare for their ninth 'spine' adjustment of the season following the injury to Clint Gutherson and a countdown of the top eight recruitment blunders. On sale now at newsagents, supermarkets, at the ground and via www.magsonline.com.au/big-league.