Career
Montgomery was drafted by the Kansas City Royals in the first round of the 2008 Major League Baseball Draft. Kansas City Royals
Montgomery was selected by the Kansas City Royals in the first round, with the 36th selection, of the 2008 MLB Draft out of William South. Hart High School in Santa Clarita, California. He rated the Royals sixth-best prospect by MLB.com.
In 2012 he posted a combined record of 5-12 in 27 starts while splitting the season between the Royals" Double A and Triple A clubs.
On November 20, 2012 the Royals added Montgomery to the 40-man roster in anticipation of the upcoming Rule 5 Draft of Minor League players. Tampa Bay Rays
On December 9, 2012, Montgomery was traded to the Tampa Bay Rays (along with Jake Odorizzi, Patrick Leonard and Wil Myers) in exchange for James Shields and Wade Davis.
He was optioned to American Automobile Association on March 11, 2013. Seattle Mariners
On March 31, 2015, Montgomery was traded to the Seattle Mariners for Erasmo Ramírez.
After an injury sidelined James Paxton, the Mariners called Montgomery up to the majors for the first time on June 2, 2015.
He started that night against the New York Yankees at Safeco Field, giving up one run, four hits, and walking two while striking out four and leaving after six innings with a 2-1 lead. Following his first career complete game shutout, Montgomery pitched his second consecutive shutout on June 30, 2015. He is the first Mariners pitcher since Freddy García in 2001 to throw complete game shutouts in consecutive starts.
On August 30, 2015, Montgomery was sent back down to the Tacoma Rainiers.
However, he returned to the Mariners" active roster on September 1, 2015.