Essendon coach Mark Thompson admits he's at a loss to explain the Bombers' startling inconsistencies during matches as they prepare for an elimination final against North Melbourne.

The Dons rode the rollercoaster against Carlton at the MCG on Saturday and escaped with a nail-biting draw that sealed seventh spot and a 'home' final.

It should have been much easier.

After trailing by 30 points at the first change, the Bombers reeled off 10 of the next 11 goals to hit the front by that margin.

But Essendon took the foot off the pedal and allowed Carlton to almost steal a thrilling come-from-behind triumph, but Bryce Gibbs' last-minute set shot fell short.

Thompson understandably cut a frustrated figure in his post-match press conference, where he struggled to explain how the Bombers could be so bad and so good in the same game.

He thought the momentum swings came down to the players possibly losing their competitive edge, becoming too ambitious or too selfish.

"I think it has to do with individuals just changing their behaviour, obviously," Thompson said.

"I think they realise it happens and I don't think they realise it happens while it's happening at the time and they've got to start to realise because they have to change it much quicker than they do."

Thompson said the players "deserved" the biggest on-field spray he's delivered this season at the first change after a "terrible" first quarter.

However, he said he tried to keep the message from being negative when he locked the players away for about 20 minutes post-match.

"It's exciting to be in the finals and we're there so we've got to try and keep it all positive and get them fresh," he said.

"We don't want to fill their heads up with negative stuff.

"Everybody in the world knows that we can play good football. I just don't know if we can play for a whole game."

The Bombers will now turn their attention to North, a team they defeated by 39 points in round one.

"It's a long way away. We won't play like that. They won't play like that," he said.

"The same players aren't playing. It really means little.

"They're a good balance between attack and defence now. They've finally sorted it all out.

"Their younger players they've had for years are becoming more consistent.

"It'll be a good game."

Thompson was unable to shed any more light on key forward Jake Carlisle's availability to face the Roos as he recovers from a hamstring issue.

"I'm no clearer than I was the other day. I don't know what's going on," he said.

"I've never seen a one-week hamstring. But they say it could be possible. I don’t know.”