West Coast co-captain Oscar Allen has avoided the worst-case scenarios after an innocuous injury late in Sunday's loss to Carlton, with the Eagles suspecting the key forward has suffered a plantaris injury. 

Allen went down behind play during the fourth quarter at Optus Stadium and struggled to put weight on his left leg as he left the ground with trainers, prompting fears of a more serious setback. 

Coach Andrew McQualter said the club's medical team had ruled out a serious knee injury but the Eagles would continue to work through the exact details, with the plantaris injury involving a muscle or tendon in the back of the lower leg. 

"That's what we think at the moment, but we'll still work through the details and get a report early in the week," McQualter said after the Eagles' 34-point loss. 

"Our medical team just briefly said that we've avoided all the worst-case scenarios and we'll work through what's next. 

"When you see a player go down with no contact off the ball like that, you think the worst. I think there's been a couple of cases of that this year, so fortunately he's avoided that.

"I saw him in the rooms just then. He's OK. Everyone that gets injured is a bit emotional, and that's just normal. And we lost the game of footy, but he's OK."

Key defender Harry Edwards will also require scans as the Eagles head into their mid-season bye, with the improved backman injuring his shoulder and ending his 50th game with ice on his hamstring. 

Sunday's loss to the Blues included an opening quarter that McQualter said was not acceptable after being wiped out in the contest and conceding seven goals to one in a game-defining blitz. 

The Eagles responded to gain a foothold in the game and kick six of the last eight goals, but McQualter said they needed to move past efforts like that, which saw them beaten in contested ball (53-33), overall disposals (123-71) and inside 50s (24-10). 

"Unfortunately, we just didn't turn up. (There were) too many fumbles, too many cough ups, too many missed tackles, and Carlton's ability to get inside to outside was just elite," the coach said. 

"We spent some time talking about that and understanding that we can't accept that anymore. We can't put in quarters like that. I don't think we've done it for a good chunk of time. 

"We just spoke about it as a group that there's a level you have to be able to compete at, and we weren't quite there in quarter one."