Wolves were beaten 1-0, with Arsenal's Myles Lewis-Skelly sent off before halftime. Joao Gomes was dismissed midway through the second-half for the hosts.
Pereira later said: "Yes. In the end of the game, I tell you we lost a big chance to win this match, because we played a very good game, in my opinion.
“Tactically, commitment, energy, we did everything to win the game. What we missed was to score, to score one goal.
“We had two chances before they scored, we had two clear chances to score the first goal. After yellow card for Joao, they scored one goal and we didn't.
“It was a game where we went head-to-head with Arsenal. With a team that we know what they have as a squad.
“We played head-to-head, we played full pitch, we tried to play our game, tried to create and we create our chances. This is the type of game that the result doesn't reflect what has happened on the pitch, but that is football.”
On Gomes’ sending off, Pereira added: “It was, but Joao gives a lot to us. He is a player that, every match, he gives 100% from himself. We talk a lot of times, and he said to me, ‘Coach, I'm emotionally balanced, I'm ok, I will control myself. Don't worry.’ But in the end, it’s football.
“The problem is that we need solutions for the midfield. We need solutions, we need to have more players with the skills to play with two in the middle. The next days, we must bring in another midfielder because we need it.”