Conte too, as far as I understood his comment, was disappointed by Caceres' defensive performance at San Siro. The coach didn't say directly how Caceres played bad in defense, but from his words ("Martin Caceres needs to do better in defensive terms, but I really cannot complain about his attacking movement tonight") it was pretty obvious imo that Conte was far from pleased.
We seem to have forgotten how bad Caceres used to play defense two years ago. Some sliding tackles, attractive ones, fooled some people, but generally Caceres was a disaster in defense. Only Marco Motta did worse than him.