The man who led the Rossoneri to two European Cups says that while the Dutchman clearly has plenty of ideas, "his game is not always successful"
Seedorf has led the Rossoneri to within touching distance of a Europa League place after 10 wins from 17 Serie A games since succeeding Massimiliano Allegri at the helm in January.
However, Seedorf's position is far from secure, with speculation rife that Milan owner Silvio Berlusconi, who championed the appointment of the 38-year-old coaching novice, now has reservations over the former midfielder's tactical acumen and preferred style of play, reservations shared by Sacchi.
“When one wants to set up a rock band, having only jazz musicians makes it difficult,” the former Rossoneri boss told Radio Two.
“Clarence has been shown to have ideas, but there is a difference between saying and doing.
“He has got some good results, but his game is not always successful.”
Sacchi then switched his attention to Mario Balotelli, whose place in Italy's World Cup squad has been questioned following some disappointing performances in recent months.
However, the 68-year-old ex-Italy coach, who led Milan to two European Cups, backed the forward to lead the Azzurri attack in Brazil.
“The great players prove such by person, from their seriousness and professionalism,” Sacchi stated.
“If Balotelli met these criteria, he should be taken.”