In 2012, Jerez started 32 games with the Short-Season A Lowell Spinners before missing the remainder of the season with hand injury. Prior to injury, Jerez batted .241 (20-for-83) with five RBI and three stolen bases. Then in 2013, he appeared in 38 games and hit a paltry .138 average in 38 games while playing right and centerfield for Lowell. But Jerez turned his career around after moving from outfield to pitcher in 2014. In that season, he posted a 3–1 record with a ERA and one save coming out of bullpen for the GCL Red Sox. He ended the season at Lowell, going 1–1 with a ERA.