Those cross field balls to the fullback that haven't really been coming off do support this, it's as if we expect them to be in more space than they are.
You do wonder if we planned our attacking moves around their fullbacks being higher up the pitch due to the three at the back, and them switching to a back 4 has messed with us.
Are commentators self aware at all? He's saying "Southampton havent really pressed the centrebacks like they normally do" at the exact time Walcott and Adams force a pass back to the keeper from the centreback.