Cabrera, 23, batted .276 (106x384) with 22 doubles, two triples, three home runs and 50 RBI in 112 games with Double A Altoona during the 2012 season.
He saw action in one game with Triple A Indianapolis during the season, collecting two hits.
Signed by the Pirates as a non-drafted free agent from Venezuela on April 11, 2008, Cabrera has batted .292 (420x1440) with 95 doubles, 11 triples,
13 home runs and 200 RBI in 408 games during six seasons at the minor league level.
Oliver, 25, compiled a 5-9 record and 4.88 ERA (118.0IP/64ER) in 28 appearances (19 starts) with Triple A Toledo during the 2012 season.