The Blues trailed 2-1 at half-time in Saturday's derby but emerged after the interval and peppered Simon Mignolet's goal.
McCarthy told evertontv: "We weren't good enough in the first half and that's a couple of times that's happened recently which the manager let us know about in the dressing room. He tore into us.
"We got the ball down and played it better in the second half, and there was a big change. The gaffer's passion is passing the ball and playing properly and even though it was a derby we managed to do that.
"There was only going to be one winner in the second half so it was so annoying to concede another set piece. I saw it going over my head and just couldn't get anything on it because it was a wee bit too high. We will have to work on that."
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