"I can only point at ourselves letting Arsenal back in the game, unfortunately, after a great effort and performance and getting into the position we wanted to be in at 1-0," Big Sam told West Ham TV.
"Arguably, had we produced a bit more quality, particularly when Mo Diame ballooned a chance over the bar when he was on his own inside the six-yard box, [we could have been further in front]. There was enough pace on Andy Carroll's ball into him to place it and be more accurate, but he's tried to blast it, which we've been going on about to him for months and months now.
"We had lots of final-third play and crosses and corners and finally got what we wanted. It was a fantastic run from Antonio Nocerino in behind the Arsenal defence and Matt Jarvis popped up to head it in after coming in from the wide position, which was perfect.
"Then, to not hold on to 1-0 until half-time was a great shame, really. Sadly, if Arsenal had scored by one of their players producing some of the outstanding genius that they have then I can't complain too much, but it really boiled down to our own deficiency in not seeing that half out. Mis-kicking a clearance straight to the opposition's midfield five yards outside the box, you're asking for trouble and that's exactly what we got.
"It was the same in the second half. We came out and controlled the second half, looking to probe the Arsenal defence and not in any trouble whatsoever, then one long ball went into our box and there was a mix-up and it was 2-1. I couldn't quite believe it on the performance that we'd given.
"Sadly, in the end, we tried to get back in the game, but even when I was going to put two subs on they went and scored the third just before I could do so and we have lost. Performance-wise, yes, but result-wise it was not acceptable and we have got to do better against a very tough Crystal Palace side."