Arsenal lost their fourth consecutive Premier League home fixture at Emirates Stadium on Monday (AEDT) – the club's worst winless run on home soil in the top flight since 1959 – with the decisive moment coming when Pierre-Emerick Aubameyang headed into his own net from Ashley Westwood's corner in the 73rd minute.
The Gunners' cause had been made harder when maligned midfielder Xhaka was sent off shortly before the hour mark for grabbing Westwood by the throat.
That was the sixth Premier League red card for the Gunners since manager Arteta took over in December 2019 – double that of any other side in the same period.
Arteta acknowledged Xhaka's behaviour was "unacceptable" but he refused to be too critical of the Switzerland international following his third red card in the Premier League.
"It was complete dominance from the start to the moment that Xhaka was sent off," Arteta said.
"The attitude of the players was amazing and the way we played in moments was really good.
"They are really willing and probably too willing. In key moments we overstepped the line and got a man sent off. By 'too willing' I mean that they are incredibly committed to what they are trying to do, they are trying their best.
"We took the energy we played with into the wrong place because in that moment we were left exposed.
"We know that these things are unacceptable and the moment that we are in now it's even more so."
Arteta's position will come under further scrutiny after a seventh Premier League defeat of the season that left Arsenal 12 points off the pace and just five points above the relegation zone, but left-back Kieran Tierney said it is the responsibility of the players to correct their dismal form.
"We are not showing the manager what we can do and how much we believe in him," the Scotland international told Sky Sports.
"Every game there are signs we are doing a bit better but it is still not good enough. It is hard to say the red card cost us the game. It was always going to be a lot tougher.
"Hard work is the only thing [that can fix this], nothing else for it. There are no excuses. There is nothing I can say that will make people believe a positive thing is going to come out of this.
"We are lucky we have a great manager. We just need to show better on the pitch."