A.J. was a solid hitting catcher for 22 seasons in the Eastern Missouri Baseball Association, primarily for the communities of St. Paul and St. Peters. He was selected to 10 EMBA all-star teams.

During the 1970s, A.J. caught for St. Dominic High School in O’Fallon, Missouri. During the 1980s, he played for Columbia College in Columbia, Missouri.

Koenig managed the O’Fallon American Legion Post 388 team in 1999 and 2000, and then again from 2003 to 2014.  From 2016-2018, A.J. coached the American Legion Post 218 team in Washington, Missouri.

He is currently in his second year as an assistant baseball coach at DeSmet High School in St. Louis.

In 2015, Koenig was inducted into the St. Charles County Amateur Sports Hall of Fame.