It goes back way further than the current coach. Tom Hafey - with Ablett and Jackson. Blight could barely manage Ablett's over exuberance on the field. Then there was Mooney under Bomber. Wasn't he suspended multiple times in one season?
Yes, in 2006.
But in 2007 things actually changed. There was only one suspension for the entire season, and even that was very, very unlucky (Ricciuto slid into Rooke's hip in Adelaide - who was standing still - and somehow Rooke was to blame). That was the difference. Those players actually did learn to not do stupid things.