Speaking on Triple M radio, Wallace said the heavy conditions influenced Cotchin's selection after his impressive work at stoppages at VFL level.
Cotchin was selected number two overall in the 2007 NAB Draft and has come on strongly playing for Coburg after missing the entire pre-season with an ankle injury.
Wallace said the taller Adam Pattison would make way for Cotchin in the Tigers run-on side.
Wallace also flagged a changed role for veteran defender Joel Bowden who will start in the midfield and may push forward to become a goal scoring option for the Tigers.
