The Gunners were second best for much of the Boxing Day contest at the Emirates, going behind to a 34th minute penalty from Alexandre Lacazette before Granit Xhaka added a deserved second goal with a sublime free-kick just before half-time.
Bukayo Saka grabbed a third goal shortly after the restart, though Chelsea tried to mount a late fightback and Tammy Abraham grabbed a consolation goal before Jorginho missed a stoppage-time penalty.
Chelsea have now lost three of their last four Premier League matches and could have gone second had they beaten a struggling Arsenal team, with Lampard furious with the application and effort of his players afterwards.
Asked for his thoughts on the game, Lampard told Sky Sports: ‘Not good enough. First half not good enough. Second half, yeah, good enough, but mountain to climb and when you attack a game the way we did – attack is definitely the wrong word – but things like the Saka goal happen, because you don’t deserve luck.
‘We fought second half, the people that came on added speed, energy, intensity into our game, but that should be a given from the start.’
Asked why that was not the case, he continued: ‘I don’t know. That’s one for the players. I’ll take responsibility on the outside, but the players have to take the responsibility.
‘The message was clear: this is a dangerous game for us, talented team, back against the wall, London derby. We were in a good position where we could go second, and they’re in a position where they’re maybe looking downwards.
‘That’s a dangerous combination, the players knew that, we prepared for the game. But if you go out and play at 60% or 70%, or a few players play at that level, you’re not going to win any Premier League game.’
On whether he was angry with the players, Lampard explained: ‘Yeah I’m angry because I want us to win games and today was an opportunity to go second at a place where they’re having a tough time, and we know how that goes.
‘You either make it more difficult for them or you give them a little opening, a crack, and we did that from minute one and continued to do it for 45 minutes.
‘And you get what you deserve. Lazy to give away a penalty. Lazy in terms of giving away a free-kick that he [Xhaka] puts in the top corner. I’m very, very disappointed in the way we approached the first half, because some things in football are basics.
‘It’s not tactics or systems, it’s: do you want to run? Do you want to back your teammate up? Do you want to sprint? Or do you want jog? Or maybe you want to say, “Oh maybe I don’t have to run”. We took that decision rather than the right one.’
Asked if he will demand a reaction in the next game, Lampard said blunty: ‘Yeah. And the players will have to do it. It’s up to them.’