The England striker, along with boss Arsene Wenger, accepts the team keeps starting games badly.
He said: "It's hard to understand because it's happening most weeks. We didn't really have a slow start on Tuesday, it was just sloppy goals that could have been avoided.
"We've had a lot of slow starts and given ourselves a lot to do.
"That's always difficult - you're always chasing the game and you're always leaving gaps."