In 2005, Walls was involved in a feud with Sydney Swans coach Paul Roos, after Walls stated that "the Swans can't possibly win the AFL Premiership with Paul Roos' style of coaching". Walls was on the Network 10 commentary team with Stephen Quartermain and Tim Lane when the Swans suffered a 43-point defeat against at Marvel Stadium, after which they were particularly scathing and critical of Sydney's misbehaviour and overall performance in that match. This proved to be the turning point in Sydney's season, and ultimately they went on to win the flag (reversing a loss to the Saints in the preliminary final en route) after which Roos refused to accept Walls' apology.