Professional
After playing well in the 2000 Summer Olympics Casey signed a four-year contract with German club Borussia Dortmund. After finishing a year of playing with the club, Casey was loaned out in the 2001–02 season to Hannover 96, where he scored seven goals in nineteen games. The subsequent year, Casey stayed with Dortmund, but only saw action in four games, scoring one goal. In 2003–04, he was again loaned to a second division club, Karlsruher SC, scoring fourteen goals in thirty games. In 2004, Casey signed with Bundesliga club Mainz 05, but scored only two goals and struggled with injuries during two and a half seasons with the club.
After being released by Mainz, Casey returned to America and signed with Major League Soccer. Casey was originally allocated to Toronto FC[2] and after two games with no goals and no assists, he was traded to his hometown club, Colorado Rapids, on April 19, 2007, in exchange for Riley O'Neill and an undisclosed amount of allocation money.[3]
He played 15 games with the Rapids in 2007, scoring two goals and three assists. In 2008, he scored 11 goals and two assists in 21 games. Casey ended the 2009 MLS season, with 16 goals, just one less than leader Jeff Cunningham to go along with one assist in 24 games. He was named in the MLS Best XI in 2009.[4] In 2010, Casey became the All Time goal scorer for the Colorado Rapids as he scored 13 goals and 6 assists in 27 games. Likewise in 2010, Casey was selected as the MVP for the 2010 MLS Cup championship[5] though the representative of the award sponsor announced "Casey Conor" when awarding it. In 2011, Casey suffered a season-ending Achilles tendon injury[6] in a July 16 game against the Seattle Sounders FC as he finished that season with six goals and one assist in 14 games. In 2012, Casey scored two goals and three assists in 18 games. On November 16, 2012, Casey was released by the Colorado Rapids.[7]
On December 14, 2012, Casey was selected by Philadelphia Union in the first round of the 2012 MLS Re-Entry Draft, Stage 2.[8] On January 23, 2015, it was announced that Casey had signed a new contract with the club for the 2015 season.[9]
After three seasons in Philadelphia, Casey signed with Columbus Crew SC on January 26, 2016.[10] Casey received a direct red card for violent conduct just three minutes after coming into a match on June 1 against the Philadelphia Union. however, an independent panel rescinded his card and he was eligible to play the following game.[11] After dealing with injuries throughout the year, he was only able to make four appearances for Columbus before announcing his retirement.[12]
