It could be the difference between making the top eight and finals oblivion, but Newcastle coach Brian Smith says he will not start scouting NRL referees before matches.

Smith was livid with the performance of Jared Maxwell in Saturday night's 18-16 loss to the New Zealand Warriors, everything from his controlling of the ruck, to the ten metres, to his match-deciding penalty against Jarrod Mullen coming under fire.

Mullen was ruled to have been offside after a Grant Rovelli bomb bounced of Cooper Vuna's back and into Mullen's arms, Knights players believing it was a case of accidental offside with Vuna clearly not playing at the ball.

Smith wouldn't enter into the debate, save for saying: "I presume it was the right call, I hope it was for his sake because it won't change anything else."

Smith knocked back several opportunities to expand on his displeasure with Maxwell's performance for fear of attracting a $10,000 fine from the NRL.

But he could only bite his tongue so long, eventually criticising the massive ten metres at the ruck which Smith claimed was more like 15 metres for much of the game.

After beating the Knights in another close game in round four this year, Warriors coach Ivan Cleary claimed Newcastle hadn't done their homework on referee Tony De Las Heras ahead of that encounter.

Smith believed he'd been done over again, but it wasn't about to change his stance on studying the behaviour of referees.

"I never do any homework on the referees, I think the referees should not be subject to coaches and players doing homework on them," Smith said.

"(Referee's coach) Robert Finch is trying to get them homogenised so they do the same job every week.

"Perhaps they did another job on the referee by doing their homework better than us again."

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