COLLINGWOOD coach Nathan Buckley is at a loss to explain his side's continual drop-offs and has signalled that hard calls would now be made on underachieving players.

The Magpies slipped to 1-3 after a 35-point loss to Melbourne at the MCG on Sunday and now face the prospect of losing key pillars Travis Cloke (elbow) and Ben Reid (left knee) to injury for their traditional Anzac Day clash against Essendon.

Small defender Ben Sinclair (concussion) will also be assessed in the lead up to next Monday's marquee match.

"We'll be bringing in players who want to play for four quarters," Buckley said after the loss to the Demons.

"We've got enough evidence now to make calls on guys, and there's no doubt we can’t be making any compromises on the effort in the contest. 

"There's some boys who are continuing to put their prospects at risk." 

Buckley said his team couldn't afford to switch off for patches in the game, saying the responsibility rested with him to find out why it keeps occurring.

Melbourne, 17th in the League in scoring last year, kicked 11 goals to Collingwood's six in the first half as it took the game away from a lacklustre Magpies unit.

"Right now, if we stop playing for 40 minutes against any opposition, we will give them hope and belief and a chance," Buckley said.

"We have got to take that out of our make up if we want to give ourselves the best chance of performing against any opposition.

"We didn't work and the players put their hand up (and acknowledged that).

"In the end, you've got to get to the reason why? Why do we stop working? Why do we give the opposition a real crack at it? And that's my job." 

Reid received medical treatment at quarter time but fought out the game, with strapping on his knee, and was spotted with a large ice pack on his knee in the changerooms after the match.

Cloke injured his elbow in the final term and was noticeably restricted in marking contests.

"'Reidy' fought through pretty well. He wouldn't have been put out there if he wasn't right to go, but we'll assess that through the week," Buckley said. 

"And Cloke jagged his elbow and basically couldn't put his arm above his head late."

"If you're a marking player and you can't put two hands above your head, I reckon you're going to struggle, so we'll see how he goes."

Despite notching tasting victory just once this year, Buckley was adamant his side would stick together and work itself out of its current predicament. 

"We're in it together," he said. 

"There's no gaps in us. We're all in it together and we're all succeeding or failing together, and right now we're not finding our best."