United’s capitulation saw them go from two goals ahead at 3-1 to losing the game 5-3 and defensive errors were at fault for the shocking second half performance.
However, Van Persie insisted United were ready for the West Ham game after training this week.
“It shouldn’t be possible [to lose like we did],” Van Persie told Fox Sports News.
“But it still happened. We have to deal with it.
“We had a proper look at it the next day. Sometimes it was a bit confronting and it was a long meeting. One hour [or] something.
“We went from there, started again this week [and have put] a couple of really good sessions in. Everyone feels ready to face West Ham.”
Van Persie was also keen to point out how Van Gaal stressed that the defensive mistakes were a consequence of mistakes further up the pitch, spreading the blame onto the collective rather than simply United’s defenders.
“When you look at the defensive mistakes, it starts somewhere else.
“That’s where we looked at as well. It’s not just the one mistake which happens. There’s a mistake before the mistake and before the mistake, maybe positional wise. That’s where we looked at.
“Everyone knows where we have to improve.”
Van Gaal does seem to inject a sense of togetherness and camaraderie into the squad. When United win it is together and when they lose it is together, that can only help the team bond and grow as a unit.
After the disappointment of last week, United will want to get straight back to winning ways by beating West Ham this Saturday.