"It was useless," he says. "They had two shots on target and scored two goals and I am not sure if we had a shot on target, actually.
"Gillingham, having not had the best of starts to the season and having let in a heck of a lot of goals recently, wanted to keep it tight, which they did.
"Let's be fair, I can't say that we did well because anyone that watched the game will know that I am lying.
"Like the Rotherham game we have got to understand what happened and turn it round. We have Cardiff tomorrow and then a tough game against Millwall, who lost to Gillingham.
"Teams are going to want to beat us because we are the best team, supposedly.
"It sounds contradictory but we are the Premiership side in the first division and we have to appreciate that. Games like the Gillingham one are the type we are going to have to face, especially when we travel away.
"It was a bad performance and the two goals were crucial points, but the performance was not good enough and we didn't look like we were going to do much - which is sad considering the position we were in.
"I thought Rotherham was supposed to be a wake-up call because after that game the point was made that we were going to encounter that sort of performance again.
"Saturday was just like that with a lot of high balls and them not letting us play. We created half chances before the break and after it we were out of the game.
"Teams look at that and will say 'we know how to play against West Ham' and as a group of players we have to assess the situation and don what we can to make sure that doesn't happen again."
David still feels West Ham could have eked out a draw, however, and adds: "They stopped us from creating many chances and unfortunately there were two moments of, shall we say, not the best play.
"For the first, the ref has given a free-kick and Tomas has tried to help him up. The guy has perhaps made a bit of a meal of it and unfortunately the referee has deemed it that he was trying to stop him taking the free-kick or whatever.
"The free-kick is one thing but to get the 10 yards added on is not good and obviously from where the free-kick was first given, he wasn't going to score from there.
"To be fair to the lad, he has cracked a great shot and it has gone right round the post marker as well, so credit where credit is due.
"Then there was the sending-off which put us up against it, and they have scored another goal when we only had 10 men.
"So it was two moments which I think stopped us from getting a draw because I think in all honesty we weren't good enough to get the win on the day."
David absolves Trevor Brooking from any blame, however, following his first defeat as caretaker manager, and explains: "Trevor has done a fantastic job; you can't look at the manager and say he has done anything wrong.
"The performance by the players wasn't adequate and as players we have to accept that.
"I understand that Mr. Pardew is a very good manager, obviously, because we wanted him and we can't make any mistakes about the manager that takes over, so what Trevor has to do in his remaining games is win the rest of them and give Mr. Pardew a tough act to follow if you like."
David draws scant consolation that the loss, as with the one at Rotherham, was not against what might be considered as a main rival for promotion - but he stresses that the club can't afford too many more reverses.
"I suppose in some respects it is better to lose to a side that is struggling than one that is doing well," he says.
"You are apparently allowed six defeats in a season to go up so we only have four left - it is frustrating considering the way we have been playing."
As for whether manager-in-waiting Alan Pardew was watching or not, he says: "There's probably an exclusion order around him!"