James Anthony Happ is the youngest of three Happ children; the other two are older sisters. He was born in Peru, Illinois, and attended St. Bede Academy, where he played baseball and basketball. He was a four-letter winner at the school in both sports. In his last year of high school, he was county Athlete of the year.
Happ played baseball for the Northwest Wildcats while attending Northwestern University. He made the All-Big ten conference in his first three years. In his last year, he compiled a 16-11 record with an ERA of 2.88 with 251 strikeouts compared to ninety walks. Happ decided to skip his senior year when he was drafted in the third round by the Phillies. Happ was a relatively average minor league type pitcher during his years with the Phillies. Midseason 2010 he was traded to the Houston Astros. He made a total of thirteen starts with the Astros in 2010. He went 5-4 with an ERA of 3.45. The following season was the worst of his career, posting a 6-15 record. In 2012 he improved some to a 7-9 record but was again traded, this time to the Toronto Blue Jays.
During the 2012 season, he appeared in only ten games due to a fractured foot, which set him down for the remainder of the season. On May 7, 2013, he was hit in the head with a line drive, collapsing immediately and laid on the mound for over ten minutes before being removed to the hospital. He was released the next day but put on the 60 day DL with a head contusion and laceration of the left ear. That year he made a total of eighteen starts and posted a 5-7 record. Other than getting hit in the head, Happ’s time with the Jays was unremarkable as well. After the season, he was again traded, this time to the Seattle Mariners. In 20 starts, he was 4-6, again unremarkable.
In the middle of the 2015 season he was traded to the Pittsburgh Pirates, where a mysteriously new Happ appeared, he went 7-2 in eleven starts posting an ERA of 1.85. During the winter, the Blue Jays wanted him back. The Jays paid him a bunch of money, and he won eleven wins before the All-Star break, the first to do that since Roy Halladay. In August of 2016, he tied Steven Strasburg for the most wins in the MLB. In 2017 he was named to the All-Star game.