Substitutes Ryan Christie and Justin Kluivert struck the goals after Arsenal defender William Saliba was sent off on the half-hour for hauling down Evanlison.
Iraola told the Daily Echo: “I think we've been talking these two weeks about recovering these points that I think we shouldn't have lost against Leicester, considering how the game went and it's nice to recover them against Arsenal.
“Obviously, once they receive the red card, the game becomes a little bit easier.
“Not easy, but a little bit easier. But even before, I think we were doing a good game and I think it's a very valuable three points for us.”
On Christie's goal, Iraola said: “It was a key moment, I think, of the game because we had lost a couple of very clear chances at the end of the first half, at the beginning of the second.
“If you don't score in that moment probably you start to get desperate because we were having the ball, but it's always difficult not to beat a block like the one they do.
“We could see it against City when they also played with ten and it was good to make the difference with a routine at the end.
“Also, even in set plays, you still have this small advantage of having one more player and I think we could exploit it well, a good routine and lovely, lovely finish by Ryan.”
He continued: “It was going to be very difficult to find the pockets and we decided to go with Dango (Ouattara) left, Antoine (Semenyo), right, to try to make a difference wide to put good balls because probably they were going to invite us to play wide.
“The change from Julian (Araujo) to Adam (Smith, at half time) is a little bit trying to find good quality deliveries from these inside channels, from the full back, because they were protecting very well their full backs with the wingers, with Marino sometimes arriving to protect one side, with Trossard.
“After the changes of Sini (Luis Sinisterra), Justin, Ryan is to try to introduce players play better in smaller spaces because at the end it's difficult, when they put their block, we could see it against City, even top players cannot find these spaces.
“Luckily for us, we could score in the routine because otherwise it was going to be difficult.”