Development Squad coach Nick Haycock was left to rue the 'small margins' of football going against his side after they lost out to Tottenham Hotspur in their Barclays U21 Premier League opener on Monday night.
The Hammers showed good mental fortitude to get back in the contest after Daniel Akindayini gave the hosts a first half lead.
Kieran Bywater's free-kick gave West Ham the platform to try and win it themselves, but it was Spurs who took the points through Cristian Ceballos' 74th minute winner and Haycock felt his side could have been more clinical.
He explained: "I thought it was a good advert for Under-21s football - there was a healthy crowd in and the game had a real good tempo to it.
"I'm disappointed with the result because I thought it could have gone either way. There were moments when they could have asserted their authority and there were moments when we got back in the game.
"We did excellently to get back in the game and then we had a couple of chances to go 2-1 up, so it might have been a different story.
"I was pleased with the attitude of the players, but I thought we could have controlled the game a little better at 1-1.
"We stepped on to them well, which was the instruction we gave at half-time, to not let the centre backs have too much controlled possession.
"We created countless good areas, it was just that final pass, cross or finish that was missing. It was small margins and we don't want to keep going into the dressing room talking about small margins.
"The clinical finishes Tottenham showed on Monday is the difference at any level. That's where we've been found out a little tonight."
Kieran Bywater finished as the Under-18s' top goalscorer with 18 to his name last term, and Haycock says he can aim high having made the step-up this season.
He added: "Kieran has done well, he's gone back to the central midfield role he played for many seasons at the younger age groups.
"He can score from there as well. He has got good delivery from set pieces, and if it is a cross to the far post it's a great area to put it in.
"Shooting towards the far post means it has got a chance of going straight in as it did, or someone can get a touch."
The Hammers have a swift opportunity to put things right when they host Southampton at the Boleyn Ground on Friday evening and Haycock is looking forward to seeing how his team responds.
He concluded: "I said in the dressing room that when you're in the league programme you haven't got time to be sombre about a defeat because it's about how we react.
"We'll watch the clips back from the game, see the good things and bad things that we did, we'll recover with the sports science department and then we'll be back on the training field to get ready for the Southampton game."
The U21s host Southampton in their first home Barclays U21 Premier League game of the season at the Boleyn Ground on Friday night. Kick-off is at 7pm and admission is free of charge for Season Ticket Holders.
FT - Tottenham U21 2-1 Development Squad