Philadelphia Union Pfeffer then spent several months training with the
Philadelphia Union first team and made an appearance for them in a friendly against
C.D. Guadalajara on September 1, 2010. Pfeffer was a member of Philadelphia's U-17 squad that competed in the MLS U-17 SUM Cup in Houston, Texas. On December 22, 2010, the Union signed Pfeffer at the age of 15 as their first-ever
homegrown player. He made his regular season
Philadelphia Union debut on September 17 against
Columbus Crew, at 16 years of age. In the 2012–2013 campaign, Pfeffer scored 2 goals in 9 matches playing for the
Hoffenheim U-19 side.
Colorado Rapids Pfeffer was traded to the
Colorado Rapids in January 2016 in exchange for the overall second pick in the
2016 MLS SuperDraft, which was used to draft defender
Josh Yaro. In 2014 and 2015 he played in the
Major League Soccer Homegrown Game. He decided to leave soccer, to go to college and then pursue a career in finance. Pfeffer was called into the first
U-18 National Team camp of 2012 by then-Manager
Richie Williams. He was also called up to numerous U-18 National Team camps in 2012. He scored a goal in their November friendly against Canada. ==Career statistics==