Gus Poyet's men have only won once in their past nine Premier League games and while they have claimed five clean sheets in that time, their lack of goals has been critical.
Sunderland have only scored 16 goals this season - the third lowest tally in the English top flight - and have managed to hit the back of the net just five times in that nine game run.
O'Shea has a suggestion for manager Poyet, although the Uruguayan will have to abandon his preferred patient build-up play, with his Irish captain calling for Sunderland to challenge their opponents with crosses.
"The frustrating thing on Sunday [in a scoreless draw with Aston Villa] was that when you're against 10 men you know you're going to have a lot of possession but you hope to create more clear-cut chances," O'Shea told the Northern Echo.
"We got into dangerous positions and maybe we need to be that bit more positive and take people on in the box.
"Then you're putting them under pressure to get tackles in.
"We want to put crosses in and make defenders make really tough clearances, rather than put it straight onto their head.
"People might think it's all down to the strikers but it's not just them. We have to supply them. It's a team effort, as it is defensively."
O'Shea reckons Poyet's focus on improving Sunderland's defence could also be costing them up front.
"The whole team unit is working so hard together defensively and maybe that's why we're lacking the final bit of energy," he said.
"We've done a lot of work on the defensive side and that's the balance we've got to find."
The Republic of Ireland international added: "[Forwards] Connor Wickham and Adam Johnson in the first half [against Villa] tracked back well to help us out.
"Attacking-wise we need to help them out a lot more. If we can do that, we will create more chances."
Sunderland's next test is away to Manchester City on New Year's Day.
