The 23-year-old was on target in the Gunners' 5-2 victory over their North London rivals at the Emirates.
"I think the better team won," he told Arsenal's official website. "They did have some good patches but in the grand scheme of things I think we deserved to win.
"We were very ruthless going forward and had five different goalscorers, which hasn't happened for a while.
"It's funny that it's the same scoreline as last year - who would have thought that?"
Arsenal are now sixth in the Premier League table with 19 points from 12 matches.