If this game wasn’t a reality check, then what followed from Roberto De Zerbi certainly was.
At least that appeared the intention from the head coach after this first defeat of the season.
One reality is Albion won’t change their way of playing. They just need to do it better.
Another reality is that, ideally, they need to fill a gap or two which were visible to a degree in their two 4-1 wins and more obvious on this occasion.
Having (understandably) cashed in their insurance policy, Albion cannot afford to leave the back door unlocked like they did on Saturday.
They piled men forward, piled up passes and got into a whole pile of trouble on counter-attacks.
Not just how they dealt with those counter-raids but that they were allowed to happen in the first place.
This game felt a bit like a 5-1 reverse to Everton late in the last campaign (a game in which Moises Caicedo played, let’s not forget).
West Ham had the right plan, the right personnel and, like the Toffees back on that rainy Bank Holiday, a goalkeeper in good form.
Counter-attack goals from perennial Amex threat James Ward-Prowse, Jarrod Bowen and Michail Antonio put them out of reach.
But the home side, always capable of creating danger, might still have snatched some reward after Pascal Gross reduced arrears.
In that Everton game, De Zerbi felt his side were too cavalier in how they chased the game after going behind in the first few seconds.
Here, he again said they needed to be more aware of the time available.
Defeat came at the end of a week when Albion had been showered with praise.
But it was a reminder of the tests posed by the Premier League.
De Zerbi said: “We are Brighton and maybe the people are confused when they think of Brighton.
“Brighton can lose the game with West Ham. Why not?
“They can lose the game against Everton.
“Then we want to win against everyone. We are playing with courage, with pride and we want to make our fans happy, winning every game or winning the Europa League.
“But we can’t forget we are Brighton.
“YOU can’t forget we are Brighton.
“YOU can’t forget we lost three big players because we are not honest otherwise and I want to be honest.
“I will fight to win every game but for us, for our fans, for our club, we have to be clear and honest.”
After losing Julio Enciso to injury, De Zerbi said he wants a No.10 as well as a Caicedo type in midfield and one other player in an unspecified position.
The latter may well be a specialist right-back.
Here, they had found some momentum after a slow start when poor execution of the right plan caught them out.
Adam Webster tried to force a pass but saw the ball cut out by Ward-Prowse, who helped it forward.
That was when Webster should have kept it simple as he got to the ball before Antonio, rather than trying a pass back to Bart Verbruggen which fell short.
Billy Gilmour got back to block from Ward-Prowse but the ball bounced back for the Hammer to tap in.
De Zerbi said: “When we concede the first goal, the mistake by Adam Webster wasn’t the last part with Antonio.
“With the pass, he took a big risk. In another way we can play, we move the ball faster to move the opponent right and left but we have to keep the ball.
“We can’t lose the ball in that way because we were attacking with a lot of players and the first thing is to keep the ball and don’t lose the ball.
“But anyway there was the possibility to defend better after this mistake on the pass.
“But Webster is still one of the most important players and it is not a problem.”
Alphonse Areola denied Evan Ferguson soon after that goal and early in the second period before Bowen outpaced Pervis Estupinan to reach Said Benrahma’s cross and finish cleverly.
Antonio left Webster standing to drive home the third and, after Gross shot into the bottom corner to re-ignite hope, Areola’s saves from Joel Veltman and Ferguson killed hopes of a comeback.
There were also penalty shouts for handball and for a clip on Kauro Mitoma, plus a goal-saving clearance by Danny Ings from a Lewis Dunk header, as Albion swarmed towards the North Stand.
If you are going to lose, then go down fighting, attacking, giving it your all. Albion certainly did all that.
But they should not have dug themselves that hole in the first place.
Albion: Verbruggen; Milner (Veltman 72), Dunk, Webster, Estupinan: Gross, Gilmour (Lallana 60); March (72), Welbeck (Joao Pedro 60), Mitoma: Ferguson. Subs: Steele, Igor, Dahoud, van Hecke, Buonanotte Goal: Gross 81.
Yellow card: Mitoma West Ham: Areola: Coufal, Zouma, Ogbonna, Emerson: Soucek (Benrahma 39), Alvarez (Fornals 84), Ward-Prowse: Bowen, Antonio (Kehrer 79), Paqueta (Ings 85). Subs: Fabianski, Johnson, Cresswell, Cornet, Mubama.
Goals: Ward-Prowse 19, Bowen 58, Antonio 63.
Yellow card: Ward-Prowse 24 (foul), Alvarez 45+1 (foul), Kehrer 89 (foul).
Referee: Anthony Taylor.
Minimum stoppage time indicated: 4+6.
