Second-half wonder strikes from Jose Izquierdo and Pascal Gross gave Brighton the win after Javier Hernandez had cancelled out Glenn Murray's opener in the first half, and Brighton could have won by more.
“Today wasn’t very good,” Moyes admitted on West Ham's official website. “Our performance didn’t merit a result. Brighton were the better team in the end.
"At half-time we had fought our way back into the game but they scored a worldie to make it 2-1, which made it very difficult. I think prior to that we hadn’t done enough anyway."
The defeat was West Ham's first in the league since the 23rd of December, and brings to an end the Hammers' longest unbeaten run of the season.
“I’m disappointed with the defeat," said Moyes. "We’ve been on a really good run recently and we’ve picked up points and we’ve stuck at games.
"But we were never really in the game today. Right from the start, I never felt it. We gave the first one away, we gave the third one away and, actually, I think we should have dealt with the ball from the corner before the second goal."
David Moyes has just been in the press conference, saying his #WHUFC side never got a grasp of the game and contributed to their own downfall. True enough. Gave the ball away for 2 of the goals. They were sluggish, cumbersome and lacked urgency (except 15 mins end of first half).— Jacqui Oatley (@JacquiOatley) February 3, 2018
West Ham fielded an unchanged team from their midweek draw against Crystal Palace, and are currently suffering from several injuries to key first-teamers, but Moyes refused to make excuses for the defeat.
“Brighton played in midweek as well, so there’s no excuse from it," said the Scot. "Every club has got injured players and the quicker we get them back, it will help us.”