Iraola says United had their chances, but goalkeeper Kepa's form was key for the win on Sunday.
He stated: "It's an important win for us. We won 3-0 but it was more difficult than it looks when you see 3-0. I think we've been quite solid, it was a mature performance. Kepa's performance has helped us this year.
"He has been very good in possession and with positions. I think he is confident and in a very young defensive line, we need players with experience.
"I am happy that we were more clinical today. We scored from a set play. I think it was a solid performance. Not amazing, but it was solid. We kept playing the same way and pushing until the end. After half-time we regrouped and we were better in the second half.
"I value the 28 points. I think the amount of points we have is good. At Christmas, it is a good amount."