Aaron Cresswell admitted the Hammers only had themselves to blame for Saturday’s 2-0 defeat at Cardiff City after starting both halves slowly.
The Bluebirds scored after four minutes through Junior Hoilett, before doubling their advantage seven minutes after the break thanks to Victor Camarasa’s close range finish.
Cresswell was frustrated by the Hammers’ generosity in handing their hosts the initiative and he said the performance fell below their standards.
“The start to the first half wasn’t great and them getting the early goal put us on the back foot,” he said.
“[You can’t let their player] be in so much space three yards from goal, so we’ll have to look at that in the week and focus on our next game.
“We knew it was going to be a tough game with the way they set up to play and they certainly did that.
“We couldn’t get that goal to put them on the back foot. Dec was close when he hit the post and we had a few half chances, but not enough. We weren’t good enough.”
West Ham now have back-to-back home games to close out March, with Cresswell keen to return to form as quickly as possible.
“We’ve got Huddersfield and Everton coming up, so we want to be taking maximum points to kick-on again,” he added.