After going undrafted in 2009, Yates signed with the Tampa Bay Rays. In 2012, Yates reached the Double-A level with the Montgomery Biscuits, where he had a 2.65 ERA and 94 strikeouts in 68 innings over 50 games. Yates was a Triple-A All-Star in 2013, putting up a 1.90 ERA in 51 games for the Durham Bulls. Yates was added to the Rays 40-man roster on November 20, 2013. Yates was called up to the majors for the first time on June 7, 2014 and made his debut that day. In 37 games, he posted an ERA of 3.75 in 36 innings, striking out 42. The following season he struggled, posting an ERA of 7.97 in innings for the Major League club as he shuttled back and forth between Tampa and Durham. The Rays designated Yates for assignment after the 2015 season.
On November 25, 2015, the Rays traded Yates to the Cleveland Indians for cash considerations. Yates was subsequently designated for assignment on January 5, 2016. On January 8, 2016, the Indians traded Yates to the New York Yankees in exchange for cash considerations. Yates made the Yankees' Opening Day roster in 2016. Yates pitched in relief for the Yankees for most of the season, although he was optioned to Triple-A Scranton/Wilkes-Barre on June 28, and then recalled on August 17. In 41 games for the Yankees, he posted an ERA of 5.23 and 50 strikeouts in innings.
Los Angeles Angels
After the 2016 season, the Los Angeles Angels claimed Yates from the Yankees on waivers. He was designated for assignment on April 2, 2017, after failing to secure a spot in the Angels bullpen during spring training, and he was outrighted from the 40-man roster and sent to the Triple-A Salt Lake Bees after clearing waivers on April 5. Yates made his Angels debut as a reliever on April 22 against the Toronto Blue Jays but was designated for assignment the next day.
On April 26, 2017, Yates was claimed off waivers by the San Diego Padres. He excelled relieving for the Padres, striking out 87 in innings and going 4-5 with a 3.72 ERA in 61 games. Yates credited his success to the development of a split-finger fastball in the spring which he began throwing more often with the Padres. In 2018, Yates began the season as the setup man to closer Brad Hand. He briefly went to the disabled list in early April with an ankle injury, but returned after two weeks. At the trade deadline, the Padres traded Hand, thus handing over the closer role to Yates. He ended the season with a career low 2.14 ERA in 65 appearances. He was 12 for 13 in save opportunities and struck out 90 in 63 innings. In 2019, Yates was selected as the Padres' sole representative at the All-Star Game. For the season, he led all major league pitchers in saves, with 41. He also recorded a 1.19 ERA and struck out 101 batters in innings.
International career
At the conclusion of the 2018 season, Yates was selected to represent Major League Baseball at the 2018 MLB Japan All-Star Series
Personal life
His brother, Tyler Yates, also played in Major League Baseball. Kirby married his long time girlfriend Ashlee on January 2, 2016. She owns a business that places sitters with professional athlete families, Homerun Sitters LLC.
