Robertson originally pitched for the Buffalo Bisons, the Indians' AAA-class affiliate in the minor leagues. He played with them for the first three months of the season, with the exception of one game on April 20 against the Kansas City Royals. In 14 appearances with Buffalo, 12 of them starts, Robertson had a 4–5 record with a 7.27 ERA. The Indians called Robertson up to the major league roster on June 25 after placing Rafael Betancourt on the disabled list. In eight games for the Indians, Robertson had a record of 1–1 and a 12.21 ERA. In his final appearance in the major leagues, a July 21 game against the Chicago White Sox, Robertson was ejected after hitting Magglio Ordóñez with a pitch in the fifth inning.