Two points and 10 errors - those figures will be keeping Melbourne Storm skipper Cameron Smith awake, mulling over what might have been.

The defending NRL champions are on early holidays after being dumped out of the finals with an upset 18-16 loss to Newcastle.

The shock defeat hurt even more coming on the Storm's home turf, where the Knights hadn't won since 2004.

While the Knights' victory was deserved, the Storm let their title defence slip on the back of an error count of 10.

A glaring one came two minutes after half-time when the usual safe-as-houses Billy Slater dropped a routine bomb by Jarrod Mullen which led to a try and an 18-4 lead for the visitors.

"I'll probably have a couple of sleepless nights over the next week, pondering what could have been this year," Smith said.

"We weren't good enough against the Knights and we weren't good enough this year."

Smith was still proud of his club's achievements, pointing out that playing finals football wasn't a given.

"It's hard in this competition to get all the way every year," he said.

"This is our worst result, taking out 2010 (when they played for no points due to salary cap infringements), since 2005 when we haven't made a prelim or made a grand final.

"To me that gets lost in the result this year but that's a fair achievement for an organisation to do that in this competition."

Melbourne coach Craig Bellamy said post-match he felt his side lacked the usual "September buzz" and halfback Cooper Cronk described it as the "x-factor".

"We just didn't have that x-factor that you need at finals time," Cronk said.

"Sometimes you just need to applaud the opposition and give them respect."

Cronk also lamented the uncharacteristically high error toll by his usual clinical side, including from himself with some of his kicking failing to find the mark.

"We kept coming and gave it our best shot," he said.

"We came up short and a couple of errors in my kicking game didn't help but it is what it is."

Cronk will have a new partner in the halves next year, with Gareth Widdop signed to St George Illawarra and Brett Finch retired.

"Whatever happens I'm sure whoever they choose will fit into our structures but I'm not too worried," Cronk said.

"We're a good footy team and we work hard so when you put those two things together anything is possible."