Thomas Vermaelen knows how dangerous Arsenal are but says it could be even worse for opposition teams if they tightened up in defence.The Belgian centre-half, who has sizzled in his first two months with the Gunners, believes that the team can improve even further if the defenders create a healthy balance between defence and attack."To win a match 6-2 is a big message," Vermaelen said after Arsenal's romp over Blackburn."Now we just have to continue."In the end it was a great result, but if you analyse the match, in the first half we were not so good."The first half was a little disappointing for us as a defence because we gave away too many chances and they scored two goals. That is something which we must improve and there are things we can work on."