Matterson's record with Cas (58 wins, 4 draws and 86 defeats according to wiki, if we trust that) doesn't look too bad, for a team that had to rebuild after relegation, and sell players from time to time. But in that promotion season of 2007 they won 17 of 18 league games and their play-off games, so his team's SL record then looks pretty poor.
On the plus side, he seems to be well thought of down under, and he is familiar with how things work over here. And looking more closely, after a difficult 2008, from 2009 to 2011 Cas won 76 league points from 81 SL regular round games - respectable.