West Bromwich Albion manager Alan Pardew has admitted he hasn't been able to find a solution to the squad's problems since replacing Tony Pulis in November last year.
The Baggies are bottom on the Premier League and have scored only 22 goals for the season.
"I think it's the toughest group to find answers with sometimes," said Pardew.
"We still have good players here who can go up a level and that's what we need to get now, players who can go up a level.
"I thought Chadli and Morrison would be coming back to me far quicker than they have.
"Daniel Sturridge getting injured was a blow. We've had a few blows and a few injuries that have harmed us. It has been tough but it's not daunting, it still doesn't daunt me. There's got to be a little bit more taking on responsibility and understanding their true worth.
"Some players here don't understand that they're better and they need to deliver better performances that they can."