Jarrod Bowen accused West Ham of “schoolboy” defending after they slumped to a 3-0 defeat by Chelsea.
The Hammers were booed off as their slow start to the season turned into a crawl at the London Stadium.
Nicolas Jackson scored twice, the first from a harmless-looking free-kick within three minutes of kick-off, and Cole Palmer added a third just moments into the second half.
“It’s a massively disappointing game, and one that didn’t go the way we wanted it to,” said Hammers skipper Bowen.
“We’re really disappointed with how we performed and the result as well.
“The goals were very easy, especially the first one which came from a free-kick – it was schoolboy stuff, you never take your eye off the ball.
“We conceded a free-kick in the middle of the pitch and we need to be savvy about it, maybe take a yellow card to stop a quick one, because a lot of teams would do it against us.
“The second goal, again, I think we were trying to get after the ball, then the striker’s through on goal and it’s 2-0.
“You come in at half-time obviously disappointed to be 2-0 down, but in the second half you have nothing to lose and can throw everything at it – but we conceded after 90 seconds which again takes the stuffing out of us.
“It was a disappointing day all round.”
It was a far better day for Chelsea, whose co-owners Todd Boehly and Behdad Eghbali put aside their reported row over ownership of the club to visit Enzo Maresca and his players following the win.
Maresca said: “The results and the points are always important in our business, but the main thing for me in this moment is to see how we progress as a team.
“We are improving many things, even if we could have attacked better, we could have defended better and we could have managed the game better.”