LONDON -- The result didn't really matter for Arsenal on Wednesday but the performance does. The Carabao Cup was never going to define the Gunners' season, yet a dreadful 3-1 defeat at West Ham raises questions that will linger beyond their fourth-round exit.
Before this game, Mikel Arteta tasked his players with showing the mindset required to maintain a high level impervious to switching competitions. It was a challenge they unequivocally failed, turning in arguably their worst performance of the season and triggering doubts about the competitions they do care about.
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"What it shows you is that in football what matters is the day," said Arteta. "What you did three days ago is irrelevant, what is going to happen tomorrow is the most important thing.
"We have to use this defeat, this pain, to prepare the best way to go to Newcastle on Saturday and win."
There was a degree of contention around the opening goal as goalkeeper Aaron Ramsdale appeared to have his shirt pulled by Tomás Soucek moments before Ben White headed Jarrod Bowen's 16th-minute corner into his own net.
Arsenal argued their case but with VAR unused in the Carabao Cup until the semifinal stage, their protests fell on deaf ears.
"If there's VAR, there's no goal for sure," said Arteta. "I understand for the referees it's difficult because of the angle and the number of people there but I don't want to use that as an excuse.
"We can still compete for the ball much better than we did and in that position. Obviously that takes [away] something in the game which is very important: momentum."
The fight drained from Arsenal soon afterwards. Bowen almost doubled the lead seconds after the restart as Ramsdale saved well but West Ham didn't have to wait long as Mohamed Kudus produced a superb control and finish on 50 minutes to double their lead.
Bowen fired in a third 10 minutes later which Ramsdale could arguably have done better with, even if it took a slight deflection off Jakub Kiwior on the way through. Ramsdale has had to wait since the previous round at Brentford on Sept. 27 for a chance to impress as David Raya usurped him in goal but he did little here to advance his case.
Arteta believes Raya is more adept at playing out from the back. Ramsdale had the worst pass completion rate (74.1%) of any Arsenal player here and West Ham had five shots in the entire match, scoring three times.
Kai Havertz spent the evening on the periphery after a bright early start, Oleksandr Zinchenko was hauled off after another shaky defensive performance while Fabio Vieira took a step backwards after several promising displays as a substitute.
But this was not a night about individuals for Arsenal. This was a collective failure to take responsibility which will have infuriated Arteta, a throwback to the early dark days of his reign when he had a battle to win the dressing room.
Arteta denied it afterwards but the introduction of Bukayo Saka and Gabriel Martinelli at 3-0 down felt like a pointed message to his underperforming players, one he doubled down on 10 minutes from the end when introducing Martin Odegaard despite resting him last weekend as he manages a hip problem.
Odegaard scored a smart consolation goal deep in stoppage-time but it did little to mask the mess that came before.
"I'm very disappointed," said Arteta. "I'm responsible for that. We're out of the cup and we wanted to play a very different game. Especially we wanted to compete in a very different way, the way we discussed for 48 hours, in a very different way to what we've done."
Before Odegaard, Saka and Martinelli came on, Declan Rice made his first appearance at London Stadium since leaving the Hammers for £105 million in the summer. A mixture of boos and applause greeted his return and those disparaging their former captain revelled in the lack of impact Rice and his more vaunted colleagues made.
"Maybe we are becoming quite a good cup team," said West Ham boss David Moyes. "I want to be a really good league team if I can be. But, if I can't quite do that, then I have to do well in the cups if we can."
Arsenal have proved themselves a "really good league team" under Arteta. But to maintain and improve that reputation, nights like this have to be left behind quickly.