Tony McMahon, Dave Kitson and Nick Blackman scored the goals as last year's Bramall Lane scoreline was repeated at the Kassam Stadium but Wilder was happy with his team's efforts.
He said: "We wanted to show what our true game is and we did that, I felt.
"But in the big moments we didn't show the quality that they did.
"Their boy (Blackman), for instance, did a fantastic job for the third goal.
"We tried to open them up and we did so at times. It was a bit disappointed that in the two or three moments when we had a real opportunity to score we didn't take them.
"If when you have good chances you don't put them away against this kind of opposition, you are made to pay.
"And they are a good team at the top of their league. Hopefully we can get to the top of our league.
"But the first goal was never a free kick. I just get so frustrated with some of the people who officiate our games."