After the 1971 season, Kison threw 92 innings for San Juan in the Puerto Rican Winter League. This led to a "tired arm," which caused him to begin the 1972 season on the disabled list for the Pirates. After returning, he joined the bullpen for the Pirates, posting a 2.22 ERA through the end of May. In June, he replaced Bob Johnson in Pittsburgh's starting rotation. In 32 games (18 starts) for the Pirates, he had a 9–7 record and a 3.26 ERA. Again used as a reliever in the playoffs, he made two appearances in the 1972 NLCS, earning the win in Game 3 by pitching scoreless innings over the Cincinnati Reds. However, the Reds would win the series over the Pirates in five games.