Lyon believes Fremantle's skill execution, decision-making and poor tackling was to blame for a sloppy first half against the Sydney Swans last Saturday, and has asked his players for a significant improvement ahead of Friday night's clash with North Melbourne at Patersons Stadium. 

"I thought our skill level was really low and our tackling effectiveness, which we've had a look at," Lyon said.

"At half-time there was only three (inside 50) entries different and they hadn't scored really heavily. Our efficiency with the ball, our skill level and decision-making and leading patterns … meant we had 21 entries and kicked two goals.

"(We've) just been a bit inconsistent. I think when you lose, everything looks a little bit off."

Suspensions and injuries continue to cause headaches for Lyon and his match committee. Lyon has already publicly berated Hayden Ballantyne for getting suspended this week, and Michael Walters' long-term injury means the search is on for a lively small forward.

Lyon's preference is for a like-for-like replacement, saying that Hayden Crozier is the most likely to come into the side after travelling to Sydney as the emergency last week. 

Tommy Sheridan gathered 32 possessions and kicked a goal for Peel Thunder in the WAFL last Friday and has put himself in the frame for selection. 

"Do we take a Danyle Pearce out of the midfield, who's quite small and quick, and put him forward and replace his wing role with Tommy Sheridan, that's sort of what we're looking at," Lyon said. 

The Dockers are also searching for more output from Chris Mayne. The 25-year-old has kicked 39 and 37 goals in the past two seasons, but has managed just a single goal in four games this year.

Lyon conceded Mayne should have been subbed out of the loss to the Swans, and says the ankle injury that caused him to miss the previous match against Essendon is not related to his form. 

"We probably should've subbed out Chris Mayne rather than (Matt) Taberner but we went with the experience," Lyon said.

"I wouldn't have thought he was underdone, he just didn't deliver. 

"He just needs to get going and deliver."