The Latics goalkeeper was named man of the match after a string of good saves against the Tractor Boys.
McCarthy highlighted his sides impotence in front of goal as a major problem over the last few games.
Speaking after the game he said: "We have gone to Reading, QPR and Wigan now and should have taken points from all those games.
"I'm not going to have that - 'we've had a tough start' line. We are where we are because we have not put the ball in the net. It's the same today, we've had plenty of chances but not taken them.
"We've made two mistakes at the other end and been punished for them and that's costing us. Gerks [Dean Gerken] made an error for the second one - but it's an honest mistake. He should have headed it out but because we are running out of time, he tried to keep the ball and he's got caught out.
"He's apologised but he's been excellent for us. I've been really pleased with him."