Olivera worked out at the Dodgers training facility in the Dominican while waiting for his visa to travel to the U.S. to be approved, which finally happened on May 11, 2015.[9] He passed his physical on May 19 and officially signed his contract.[10] The physical also revealed that, contrary to previous reports, he did not need elbow surgery.[11] The team announced that Olivera would spend several weeks at their spring training facility in Arizona before joining a minor league team.[12] On June 3, he was assigned to the Double-A Tulsa Drillers of the Texas League to begin his professional baseball career.[13] He made his debut with the Drillers the following day and had one hit in four at-bats with two walks in a game against the Midland RockHounds. This was his first game action since the 2013-14 Cuban season and manager Razor Shines said of him, "For a guy that hasn't played in that long, his at-bats were really good."[14] In six games for the Dillers, Olivera batted .318 and hit a grand slam.[2] He was promoted to the Triple-A Oklahoma City Dodgers on June 12.[15] His advancement was hampered by a hamstring injury on June 20.[16]