Boateng said: "At the drop ball the referee didn't know who should have possession so I said 'give it to United to give it back to our keeper'.
"But Rooney didn't want that. He wanted to compete for it. I said 'fine, let's do it,' then he lost it a bit. He's a temperamental player, who plays from the heart.
"He is an outstanding player but gets frustrated when things aren't going right. You can't take that out of him because it's part of what makes him so determined to win. He's got fire.
"At that moment Rooney got booked and the tackles started going in. They had to, because United knew if they didn't step up a gear, get more fiery, we might score again."
Boateng added: "It wasn't just Rooney but the whole United team who were getting frustrated. Look at the penalty Rio Ferdinand gave away.
"Normally, he would stand up in that situation but, because of the way we were playing, he was doing a lot of running and he was getting disappointed.
"That's when they realised they had a game on their hands! I was really hoping we could get an equaliser - then go for the win. It was there. It could have happened."