[2] He was recruited from Coburg Amateurs by the Carlton Football Club and made his senior VFL debut with them as a tall, skinny 16-year-old on 22 April 1967 against Hawthorn at Princes Park.
He was judged Man of the Match in the 1972 VFL Grand Final when he kicked six goals against arch-rivals Richmond in a masterful display.
1984, with injuries plaguing the club and its lack of depth apparent, was initially disappointing but a remarkable recovery saw them enter the five after the final round only to be crushed by Collingwood.
[14] In 1985, the Lions' financial crisis emerged to threaten their future and this, along with more injuries, caused them to drop to ninth with only seven wins and two losses to last-placed St Kilda.
[18][19] Thanks in part to an influx of interstate recruits including South Australians Stephen Kernahan, Craig Bradley and Peter Motley, Walls had immediate success in his first year at the club taking the side to a Grand Final in 1986 and a premiership in 1987.
Walls was sacked as Carlton Football Club senior coach after the team lost a home match to the lowly Brisbane Bears in Round 10, 1989.
[26][27] Walls ended his tenure as coach of Carlton Football Club with 84 games (55 wins – 29 losses – 0 draws).
[10] It was revealed in the video "Passion To Play" that in Walls first year as Bears coach in 1991, as disciplinary action Walls authorised his players to don boxing gloves and beat 21-year-old teammate Shane Strempel repetitively in the head[32] until he was severely bashed and bloodied after which Strempel quit playing football.
He became a columnist for The Age in Melbourne (a role he continues to fill), and joined the Seven Network providing special comments during AFL matches.
When Seven lost the broadcast rights for AFL matches at the end of 2001, Walls was recruited by both Network Ten and the now defunct AFL-dedicated Fox Footy pay television channel.
He provided special comments during match broadcasts, and was a member of Fox Footy's On the Couch with Gerard Healy and Mike Sheahan from 2002 until 2008.
He then switched to the One HD Monday night program with Stephen Quartermain to co-host the new football discussion show One Week at a Time.
Walls was on the Network 10 commentary team with Stephen Quartermain and Tim Lane when the Swans suffered a 43-point defeat against St Kilda at Marvel Stadium, after which they were particularly scathing and critical of Sydney's misbehaviour and overall performance in that match.
Current Adelaide coach Matthew Nicks was one of the players singled out, and he was dropped following the match; he never played again as he retired before the end of the season due to injury.
[39][40] 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 Walls unsuccessfully attempted to apologise to Roos.
[41] Although no longer a television commentator, Walls continued as the "Special Comments Man" for Sports radio station SEN as well as appearing on its Crunch Time Saturday AFL preview program alongside Anthony Hudson, Dermott Brereton and Herald Sun journalist Mark Robinson for two years before retiring.
David went on to represent Norwood in the South Australian National Football League (SANFL), but his career was affected by three knee reconstructions.