Academy Director Tony Carr admitted that defensive errors, missed chances and a lack of concentration had cost his side dear in Saturday's 4-2 FA Premier Academy League defeat at Southampton.
Jack Werndly scored twice for West Ham United at the Saints' Staplewood Training Ground, but it was not enough to prevent the home side from taking all three points.
Carr was disappointed with his team's all-round performance in what was their final away fixture of an inconsistent season results-wise. "We went 1-0 down from a Southampton corner when we should already have been two goals up, having missed two good chances through Jack and Danny Subuola.
"Matthias Fanimo did some good work down the left and he crossed for Jack to equalise, but we were behind again before half-time. They had a counter-attack and our two centre-backs were very static and allowed their striker to nip in between them to score.
"It was very poor defending to put us 2-1 down at half-time. We then conceded another goal shortly after the break before Jack scored again to make it 3-2 and we then put them under some pressure. Unfortunately, they then broke away again and made it 4-2 with virtually the last kick of the game.
"It was a really disappointing performance. Their passing and movement caused our centre-backs Callum McNaughton and Paco Craig all sorts of problems."
The West Ham squad had left Little Heath at 7.30am on Saturday, but Carr refused to blame either the early start or 100-mile coach journey for his team's defeat.
"Maybe the trip can effect you at the beginning of the game, but you quickly get into it, so I would never use that as an excuse."
The Hammers complete their FA Premier Academy League campaign with the visit of fellow Group A side Charlton Athletic to Little Heath on Friday, with kick-off at 12noon. Parking and admission are both free of charge.
Victory would see West Ham leapfrog Fulham to finish fifth in the ten-team table. Arsenal have already wrapped up the title.