As a player, Patrick featured prominently for American University, serving as co-Captain during his senior season and earning All-Patriot League First Team honors his senior season. During his time with the Eagles and he was also named Offensive Player of the Week and was on the Patriot League Honor Roll all four seasons. 

At Bethesda-Chevy Chase HS, Mehlert lettered 4 years on the Varsity and won a MD State Championship in 2007.  As a senior Captain, his accolades included All-Met Honorable Mention, All-County First Team, All-Gazette Second Team, and All-State Second Team. At the club level Mehlert played Youth Soccer for BSC, Pachuca FC, and Potomac SC.