Burnley boss Vincent Kompany accepted defeat at Brentford on Saturday.
The Bees blew the visitors away 3-0 on Saturday.
Kompany said: We didn't start at the levels that are required for this league but then in the second half we started so well and looked like we were in the game.
I think going into the first half just 1-0 down was flattering for us. They could have scored more, that's the truth. The reality is you can't afford to give any moments like this away and its cost us.
Fighting for second balls, winning tackles, things like that, you don't have any luck in this league if you aren't doing these things.
We have shown we can have good moments but in the first half we didn't really do that. It's simple, overall it's not good enough."
Kompany added: In the second-half, we came out and did exactly what we should have done from the start. It looked like there was flow to our game, we created chances, we recover a lot of balls.
"We played really well for that spell of time but there are moments we don't take and moments that they take with a fantastic goal, which put the game a little bit past us.
But even then, we are still relatively dangerous with a big, big chance at 2-0 for us. But then of course if you don't take your moment. But what happened with the red card and going down to 10 men, I don't think we can accept that.
I've given you an honest feedback but any time in the Premier League I'm telling you for 45 minutes it wasn't good enough, you can't have 45 minutes like we did in the first-half."