The Black Cats are still looking for their first Premier League win of the season, but O'Shea insists that their poor form is not down to a lack of effort.
He said: “If we can improve the concentration, then the effort is there on the training ground and hopefully it will turn quickly.
“It’s one of those things, you have to make sure you do your work on the training ground, make sure you prepare properly for games.
“We need to get clean sheets and then hopefully get the supply to the strikers to score for us.”
Sunderland are currently propping up the Premier League table, having taken just two points from their opening seven matches.
It has been a disastrous start to the season, which has left them four points adrift of safety already.
Sunderland have narrowly avoided relegation over the past two campaigns, but there are fears that this season may not have such a happy ending.
The Black Cats have looked porous at the back, and have conceded more goals than any other side in England's top-flight (16), and they have also lacked a goal threat.
It means that a huge improvement will be required if they are to start to moving away from trouble, with a match against high-flying West Ham United next on their schedule.