Yoon is a 6 ft 0 in, 190 lb right-handed pitcher. With a three-quarters delivery Yoon throws a fastball at 90-92 mph (tops out at 96 mph), a change-up, an occasional curveball, and a hard-breaking, mid-80s slider. With a shoulder injury his fastball dipped into high-80s, and he converted to relief during the 2013 season.
In 2007, Yoon joined the starting rotation due to the Tigers' ace Han Ki-joo's transition to a closing pitcher. Yoon had a 7-18 win–loss record with a 3.78 ERA as a starter. While his ERA was decent, he had poor run support in 18 of his losses, the most in the 2007 season. This gave him the nickname "The Unfortunate Ace". In 2008, Yoon emerged as one of the most consistent pitchers in the KBO league, going 14-5 with a 2.33 ERA and 119 strikeouts in 1542⁄3 innings pitched. He won the ERA title and finished runner-up to Kim Kwang-hyun in wins.
In August 2008, Yoon competed for the South Korean national baseball team in the 2008 Summer Olympics, where they won the gold medal in the baseball tournament. He was 2-0 with a save, a 2.34 ERA and six strikeouts, pitching 72⁄3 innings in five games as a utility pitcher. In March 2009, Yoon competed for the South Korea national baseball team] in the 2009 World Baseball Classic, where he went 2-0 with a 1.13 ERA and 13 strikeouts in 16 innings pitched, appearing in 4 games. He started against Venezuela in the semifinal game, and led South Korea to a 10-2 victory. Yoon baffled the South American major league all-star squad, allowing only two runs and seven hits in 61⁄3 innings pitched.
In the beginning of the 2009 KBO season, Yoon became the Tigers' closer again as Han Ki-joo was put on the disabled list. As a closer, he posted seven saves with a 2.45 ERA. Yoon returned to the starting rotation but was put on the disabled list for a month. In July, he returned from the injury and won all of his 7 decisions as a starter. However, he had the worst pitching performance in his pro career on September 5, allowing 10 runs in 31⁄3 innings against the Doosan Bears, and was then sidelined with a shoulder injury for the rest of the season. Yoon finished the season with a record of 9-4 with 7 saves, an ERA of 3.46 and 117 strikeouts in 1192⁄3 innings pitched which didn't enable him to qualify for the ERA title.
Yoon was named Most Valuable Player (MVP) for the 2011 season. He received the KBO's highest honor for leading the league in four pitching categories, marking a 2.45 ERA, 17 wins, 178 strikeouts, and a .773 winning percentage in 1721⁄3 innings. He is the first pitcher to stand at top of four categories since Korean pitching legend, Sun Dong-yeol accomplished the feat in 1991.
A free agent after the 2013 season, Yoon announced his intentions to play in Major League Baseball. According to unconfirmed reports, Yoon has agreed to a three-year contract, worth US$5.75 million, with the Baltimore Orioles. On February 17, 2014, Yoon has passed his physicals and officially signed by the Orioles. Yoon pitched for the Norfolk Tides of the Class AAA International League, where he had a 4-8 record and a 5.74 ERA in 23 appearances. He was outrighted off the Orioles roster on August 30, 2014.
The Orioles opted not to invite Yoon to spring training in 2015. He chose to return to Korea rather than report to the Orioles' minor league camp. The Orioles released Yoon, with Yoon agreeing to forego the remainder of his contract.