Having been 2-0 ahead through Gabriel Martinelli and Kai Havertz, the Gunners allowed Villa to fight-back to draw 2-2 via goals from Youri Tielemans and Ollie Watkins.
"We competed well. To get something here is very difficult. To compete like we did is the only way. They were controling and pushing more (earlier on). We had to defend strongly.
"The second half we reacted well. The mentality we showed is the mentality we want. We needed the goalkeeper, the defenders. We were always trying some transitions. Fantastic job. Now we are in good balance. We are fighting with really strong teams. How we started the second part of the season has been good.
"(We thought) scoring one goal could open the match for us and it did."
On being set to bring off Watkins before the goal, he added: "Yes I wanted a change with a fresh player like (Jhon) Duran but after his goal I tried to take my time."
On being booked, Emery insisted: "I don't know. I kicked the ball. I only kicked the ball in the direction of the players. I didn't deserve a yellow card."