This is interesting.
Perth are not out of the playoff picture yet so Sage obviously feels that a different voice/tactics is needed or that the coach has lost the changing room. Teams that change coaches usually come out firing for 1-2 games. Either way, he has only have made this change if he wants to push into the 6. Why else get someone else in for 6 rounds?
Of more interest is who comes in for the push. The cupboard is not exactly flush.