Matri joined the Rossoneri in the summer after an 11m fee was agreed with Juventus.
"Matri has always shown excellent qualities in front of goal," Ganz, who spent two years with the San Siro boys, told Ita Sport Press.
"Evidently he doesn't have the calmness right now to stick the ball into the back of the net.
"Nevertheless, I'm convinced that Matri will eventually be an important player for Milan. He will score vital goals for the cause.
"He is not a problem for the Rossoneri."
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