Hall of Fame shortstop Ernie Banks pinch-hit for Kasko in the eighth inning and replaced him in the field.

After the 1966 season, his only campaign with Boston, Kasko retired as an active player and managed the Red Sox' Triple-A clubs, the Toronto Maple Leafs (1967) and Louisville Colonels (1968–69), to a cumulative 213–213 record and one playoff berth.

During Kasko's four-year managerial term, he incorporated young players such as Carlton Fisk and Dwight Evans into the Red Sox lineup, converted relief pitcher Bill Lee into a successful starter, and showed patience with sore-armed veteran Luis Tiant as he returned to form.

But when the 1973 Red Sox again could not measure up to the powerful Baltimore Orioles of the era, Kasko was reassigned to an executive scouting position within the organization and replaced as manager by Darrell Johnson upon season's end on September 30.

While he was scouting director, the Red Sox drafted and signed impactful players like Roger Clemens, Marty Barrett, Ellis Burks, Mike Greenwell, John Valentin, Tim Naehring, Jeff Bagwell, Curt Schilling, Brady Anderson and Mo Vaughn, although Bagwell, Anderson and Schilling became stars for other teams after Boston traded them for veteran talent.