The 28-year-old, who scored the second in City's 3-2 victory, has also worked hard in pre-season, according to Platt.
"Carlos has worked ever so hard in pre-season. He has really attacked his work and not had one day off," he told the BBC.
"His goal was one of those you can remember him doing two years ago. He ducks inside, he goes away from people. That's what he's been missing and it was there again."
City open their Premier League campaign at home to Southampton next Sunday.