The £25.5million signing has been troubled by niggling injuries since his summer move from city rivals Manchester United.
However, Bowen believes the Argentina international, who has scored twice in six Barclays Premier League matches, is almost back to his best.
"Carlos probably isn't operating at 100% yet," said Bowen. "He is carrying bumps and bruises to his ankle and back, but he's playing well enough despite that.
"In terms of his sharpness and match fitness he will get better, so the best is yet to come from Carlos in the weeks ahead."