West Ham United Under-18s suffered a disappointing 4-0 FA Premier Academy League defeat by Fulham on Saturday.
The Hammers were two goals down by half-time at Little Heath, with the Cottagers adding two more after the break.
Academy Director Tony Carr said his young players would have to learn from their mistakes if they want to put an end to their losing run at Charlton Athletic on 30 October.
"We had our moments in the game - we should have had a penalty and the referee apologised to me afterwards for disallowing a goal for offside that he should have allowed," said Carr.
"The main problem we have is that we are letting in goals far too easily. We started OK and could have scored, but then we conceded. We looked like getting back into the game and then we conceded a second goal. Every time you concede a goal, it's back to square one.
"Our recent results suggest we are not getting the level of performance from the players that is required. They are not showing the form that attracted us to them in the first place."
While recent results may not have been good, Carr urged the club's supporters not to be too concerned.
"I have always said that performances and not results are the most important thing at youth level. Our job is to produce players for the first team in the future.
"Even if you are winning every game, it doesn't necessarily mean you are a fantastic team full of fantastic players. It is important not to get carried away with results, whether they are positive or negative.
"It happens in football and we have got to get on with it. We now have a two-week break before we play again at Charlton and we will work long and hard to solve the problems we have been having.
"We have been conceding goals too easily and it is giving us a mountain to climb every week. It is making things difficult and we have to make sure we defend better in future, both individually and as a team."
West Ham United U18s: Cowler, Young, Driver, Craig, Sanchez, Hall, Wearen (Purdy 89), Moncur, Vose (Powell 85), Tombides, Subuola (Lletget 70)
Subs not used: Wootton, Potts