Roy Hodgson's side were one of the top eight seeds heading into the tournament, but failed to progress from their group after losing their first two matches.
The Arsenal midfielder told talkSPORT: "We were one of the best-prepared teams at the World Cup. Our preparation was perfect. Everyone did everything that was required. I don't think we got enough credit for the World Cup.
"OK, we didn't get where we wanted to in the competition, and that was massively disappointing, but if you analyse the games a bit deeper, we did a lot of positive things that people were telling us to do.
"Unfortunately we didn't get the results we wanted, but if you look back at the videos, going forward we were excellent. Defensively we could have been better as a team, not as a defence but as a team we could have been a bit more compact and harder to beat."
England begin their Euro 2016 qualifying campaign against Switzerland on Monday.