Hailing from the small town of Brocklesby, New South Wales, Koschitzke was taken with the second overall pick in the 2000 AFL National Draft.
He debuted in round three of the 2001 season and then played every game for the rest of the year, subsequently winning the AFL Rising Star award.
His athletic 197 cm build and strong marking were a great asset to the St Kilda Football Club, which drafted him and gave him his AFL debut early in 2001.
His form continued when he kicked 16 goals over the next four games, but injury struck again after Round 21, causing him to miss the finals series.
After being a surprise inclusion for Round 6 against the Bulldogs, he was knocked out by Daniel Giansiracusa with a legal hip and shoulder.
But four weeks later he had not regained hearing in one ear and, for future health concerns, was ruled out for the remainder of the season.
On 18 June 2006, Koschitzke collapsed while appearing on a live television spot for Channel Seven's program Sportsworld while being interviewed by David Schwarz.
St Kilda staff put the faint down to a number of factors including, fatigue, dehydration and a minor virus.
[9] Koschitzke hails from the small country town of Brocklesby, New South Wales in the Riverina region, where his family has run a farm since 1922.