It was always going to be hard fro the labor government to win a consecutive fourth term. It ha a number of issues working against it. Myki, the drought, public transport and a perception of time. But the truth is Labor lost the election due to administrative error in the campaign and the process leading up to the election.
It's greatest failure was not negotiating better preference deals with the DLP and Sex party. Had the ALP manged to secure a better deal from the DLP and Sex Party alone it would have retained office and the upper-house.
The ALP lost focus and control in negotiating preferences. Its only support came from the Greens who were the ALPs main competitor in the inner city region. The ALP was always going to attract 80% of the Greens preferences but it was no assured of securing preferences from other minor parties. Parties that could have helped Labor retain office . Labor could have traded off support to the DLP in Western Victoria in exchange for support else where. if it had secure bits DLP and Sex Party support in Southern Metropolitan, or DLP support in Northern and Western Metropolitan the ALP would have won three extra upper-house seats. The ALP did not even take into consideration the upper-house. A fatel mistake. It could have traded off support for teh DLP for support in teh lower hosue. It would have also retained Bentleigh had it had managed to secure DLP preferences. Support from the DLP came at a price but the party would have retained government. without it they lost all.
The decision to introduce Optional Preferential; voting and the VEC's failure to encourage voters to fill in all squares played a significant part in the ALPs loss in Western Metropolitan but this was not the reason the ALP lost in Northern Metropolitan or Southern Metropolitan. It lost because it had no support from other players and poor preferences