J.A. Happ had a career that could be described as that of a journeyman, as he played for eight different teams, including one twice. But despite this, he had some accomplishments that other pitchers would have been proud of.

Happ was drafted by the Philadelphia Phillies in 2004 and first appeared for them in 2007. However, he was still considered a rookie in 2009, when he was the narrow runner-up for the National League Rookie of the Year award. He had a record of 12-4 and an ERA of 2.93, losing out to Chris Coghlan of the Marlins. Happ played a small role in the Phillies' World Series win, earning himself a championship title.

Despite this, Happ was traded to the Houston Astros in a deal that brought Roy Oswalt to the Phillies. This was the start of Happ's journeyman period. Over the next few seasons, he played for the Toronto Blue Jays, the Seattle Mariners, the Philadelphia Phillies again, and then back to Toronto where he had his best season. He had a record of 20-4, 163 strikeouts, and finished sixth in the Cy Young voting, his only such finish. While still with Toronto, he also played in his first and only All-Star Game, but was later traded to the New York Yankees.

Happ continued playing for the Minnesota Twins and the St. Louis Cardinals before retiring with a record of 133 wins and 100 losses.