The result in Seattle ended their campaign and ensured none of the three host nations progressed to the quarter-finals, following the earlier eliminations of Mexico and Canada.
Pochettino admitted the Americans failed to reach the standard required for knockout football – adding that the players did not execute the basics well enough and were punished by a clinical Belgian side that capitalised on their mistakes.
"We didn't show our real quality like a team. I think we never connected with the man of the game. I want to congratulate Belgium because they were good. Like I said before, it's a very good team but I think we were not on our level. I think we never connected with the game. I think we really started in a poor way," said Pochettino
"I think we never had the flow of the game. Even when we scored and the 1-1 from Malik Tillman, even in the next action we conceded the goal."
"But we analysed the game. I think it's true that today we were not the same team that during the tournament showed the quality. Very bad day. Wasn't our day in a collective and individual way."
"And we need to accept that sometimes this type of thing happens. But in a tournament like the World Cup, when that happens, you don't have another chance. You have no net. When that happens in a knockout stage, you are out and you need to go home. You need to accept that."
Asked whether the saga over how striker Folarin Balogun’s red card was reversed played any role in putting the USA team under unwanted pressure, Pochettino was clear that his side did not deliver on the pitch.
Pochettino had a positive outlook to their overall display at the World Cup when comparing the level of the opposition USA faced.
The former Chelsea boss will come to the end of his contract this month but indicated to being open to extending his stay – only if the USA hierarchy want it that way.