In February 1971, the Dodgers traded Kosco to the Milwaukee Brewers for Al Downing. He was traded again to the California Angels (for Tommie Reynolds) and to the Boston Red Sox (for Chris Coletta) before completing his professional baseball career with the Cincinnati Reds, with whom he batted .280 in 118 at-bats in 1973 on a team that won the National League West title but lost to the New York Mets in the NLCS. Kosco went 3-for-10 in that Series, including collecting the only two Reds hits in Jon Matlack′s Game Two shutout.