Chafin is from Wakeman, Ohio and attended Western Reserve High School in Collins, Ohio. He pitched a no-hitter in his final high school game. Chafin played college baseball at Kent State University. As a freshman in 2009, he was the Mid-American Conference Freshman of the Year after he had a 1.26 earned run average, eight saves and 55 strikeouts over innings pitched. In 2010, he underwent Tommy John surgery and missed the 2010 season. He returned in 2011 as a starter and had a 2.02 ERA with 105 strikeouts over 89 innings. After the 2011 season, he played collegiate summer baseball with the Orleans Firebirds of the Cape Cod Baseball League. Chafin was drafted by the Arizona Diamondbacks in the first round of the 2011 Major League Baseball draft. He made his professional debut for the Arizona League Diamondbacks, pitching in one game, recording two strikeouts over one inning. Pitching for the Visalia Rawhide in 2012, he recorded a 4.93 ERA with 150 strikeouts over. He started the 2013 season with Visalia and was promoted to the Mobile BayBears during the season. Overall, he had a 3.20 ERA and 119 strikeouts over. Chafin made his Major League debut on August 13, 2014 against the Cleveland Indians at Progressive Field, going 5 innings allowing three hits, two walks, and three strikeouts, earning a no-decision. In his second start and first Major League at-bat on September 17, 2014, for the Arizona Diamondbacks, he hit a single and got an RBI. Chafin was converted into a reliever for the 2015 season, a season in which he finished 5-1 with a 2.76 ERA in 66 games for the D'Backs. The following season, just like the majority of the pitching staff, Chafin struggled throughout the season, appearing in 32 games with a 6.75 ERA. He bounced back the following season, being used now as a situational left hander out of the bullpen. In 71 games, he had a 3.51 ERA for the D'Backs. In 2018, Chafin was continued to be used as a situational lefty out of the bullpen, pitching innings. His record was 1-6 in a career high 77 games. In 2019, Chafin appeared in 77 games for the second consecutive season, finishing with a record of 2-2 in innings.
