At least Matthew Primus now knows rock bottom.

Port Adelaide's heaviest loss and lightest score - 3.3 (21) - came in a 138-point defeat to Collingwood on Saturday night.

What horrifies coach Primus most is that he doesn't know why Port players fell apart while ignoring his instructions.

"Until we learn to play and do as you're told for four quarters ...," Primus said.

Why can't they follow orders?

"I'm not sure," he said, genuinely puzzled.

Primus is more certain about what he needs after, most likely, collecting Port's first AFL wooden spoon.

"We are a fair way down the path of knowing what we need to do at the end of this year to improve our list, and make sure it's a list going forwards, not backwards," he said.

Primus, with two lonely wins in his first full year of head coaching, knew what he was getting himself into when tasked with rebuilding Port.

"I was aware the pain we were going to go through this year by playing the core group of players we have wanted to," he said.

"But we have to go down this path, we're going to continue to go down this path.

"And there is light at the end of the tunnel, even though it doesn't seem like it for our supporters ... it's going to be feeling pretty bleak.

"But we know where we're heading and where we want to go.

"It's a long journey and a big hill to climb. We can't just roll over, give in."

Primus said he hadn't heard talk that West Australian native Jacob Surjan, once in the leadership group but now on the outer with just four games this year, wanted a trade.

But he said Port were in a battle to keep key defender Jackson Trengove from returning to Victoria while fullback Alipate Carlile has been linked with Greater Western Sydney.

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