Ramirez was drafted by the Texas Rangers in the first round of the 2007 Major League Baseball Draft out of Kempsville High School in Virginia Beach, Virginia. He then spent six years in the Rangers" farm system, playing for the Spokane Indians in 2008 and the Hickory Crawdads in 2009 and 2010. On August 17, 2011 he was promoted to Triple-A at Round Rock and substituted Eric Hurley who left on disability per viral infection.
Prior to it, on July 15, Ramirez went out for a week to rehab in Frisco, Texas due to a sore shoulder which prevented him from playing in Triple-A. He was quoting as saying to MLB.com that the absence had not bothered him.
Ramirez was added to the Rangers" 40-man roster on November 18, 2011. Chicago Cubs
On August 23, 2013, Ramirez was traded to the Chicago Cubs as the player to be named later in the July 2013 trade of Matt Garza.
On Monday June 9, 2013, he struck out 23 players while having only.71 walks plus hits per inning pitched rating. On June 5, 2014, Ramirez earned his first career save in a victory over the New York Mets.
According to Baseball America, Ramirez is 6"4", weighs 210 pounds and can throw his fastball at 97 miles per hour.