The jury is out whether Michael Maguire or Geoff Toovey can build a team from scratch. When they both took over Souths and Manly respectively there were a lot of pieces in place. Manly had won a grand final previously when Toovey took over. Maguire was successful in tinkering with the South Sydney line up, by moving Greg Inglis to fullback. Titans have talent on their roster though, so it wouldn't maybe need to be a complete start over like their doing at Newcastle.
From our 2014 grand final side the following players were either NYC, reserve grade or not at the club when Maguire took over: Johnston, Walker, Auva'a, Tuqiri, Keary, Reynolds, G.Burgess, T.Burgess, Koroisau, Te'o, Turner. He also moved Inglis to fullback, Sutton to the backrow, McQueen to the backrow, etc.
He took over a team that had Sam Burgess and Greg Inglis, and built the rest. It's disingenuous to say otherwise.