Iliman Ndiaye and Michael Keane struck for the visitors in Ipswich's 2-0 defeat at Portman Road.
“Obviously the scoreline has not been left how we'd want it to be,” said O'Shea afterwards.
“If we score a chance early on or we get that penalty decision, it's a different game.
“Going behind against these, they're going to sit back and make it difficult and that's the way the game went.”
Both goals came from balls into the box which Ipswich failed to clear.
O'Shea continued: “Yes, we knew that was going to happen with them. We've done our work on them and that's obviously what they're good at; getting balls into the box is one of their main attributes as a team.
“Obviously we need to defend them well, we need to keep the balls out and just clear our box at times.
“I think we're getting the first contact and we're winning it. We just need to clear it then and get it up the pitch so they can't score.
“But on the opposite side, we created a few chances from set pieces as well.”