The Black Cats have struggled in the Premier League since beating Arsenal in November.
“We have got to address our issues on the pitch,” said the 26-year-old. “We are far too open at the moment and I think it’s a problem.
“We are not defending well as a team and if we want to start kicking on and pushing up the league, we need to defend better as a team.”
He added: “It’s not just on defenders and midfielders – it’s on the whole team.
“Strikers need to communicate better with the midfielders and defenders, as well as the goalkeeper. It’s a thin line at the moment.”
