The Raiders now need a miracle to make the top eight, relying on the Melbourne Storm to flog Cronulla by 74 points or more and the New Zealand Warriors to beat the Gold Coast Titans.

Stuart said they shouldn't have ever been in the finals hunt after a stretch where they only won two of 11 games to sink near the bottom of the ladder.

But they rallied late in the season and went into the final round needing a win to have a chance of sneaking into the eight.

They couldn't manage it, going down 40-16 to the Sydney Roosters at Mackay on Thursday night, with Stuart labelling their attack dreadful.

He also wrapped his arm around young winger Semi Valemei, who had a tough night out, saying he'd pick him next week in a heartbeat.

In a sign of his frustration, Stuart accidently let an f-bomb slip before catching himself.

"It's an empty feeling, it's a shocking feeling, because I think we're a better team than where we've ended up on the table," Stuart said.

"But we are where we are. And that's all because of the middle part of the season where we had a really bad slump.

"We lost all our mojo and form ... and realistically we probably don't even deserve to be fighting for the eight tonight.

"We were poor tonight, we were really poor.

"If we can't beat that [Roosters] team out there tonight, we're only wasting another week being up here."

That baron spell included the departure of Williams, who was released from his contract and returned home due to homesickness.

Finding a new halfback will now be top of Stuart's to-do list over the off-season.

He admitted Williams' exit had a significant impact on the team.

"Yep, very much so," Stuart said.

The Raiders started well, but the Roosters overran them to ice the game with almost 30 minutes remaining.

They did it with their dominant forward pack, despite Jared Waerea-Hargreaves being a late withdrawal.

Siosiua Taukeiaho ran for 205 metres, Angus Crichton 167m and scored a try, and Isaac Liu 119m.

Roosters fullback James Tedesco started to wreak havoc in the second half before coming off in the final six minutes.

Valemei struggled under the high ball in the first half before getting switched from the right wing to the left.

He also made several mistakes towards the end of the game, but Stuart was full of support for his Fijian flyer, who was a late replacement for Sebastian Kris.

"There's games like that where you don't see it coming. We got to the sideline ready to go, the boys prepared well," he said.

"I can't blame our defence tonight, our attack was dreadful.

"Poor old Semi had a tough night. He's a better player than that and I'd pick him again in first grade next week - that's not him.

"In the second half we just took so many wrong options in attack. We didn't give ourselves a chance to attack because we took the wrong option with the football."