In 1985 home field advantage in the league championship series was done on a rotating basis. In the American League it was East even years, West odd years. Why where the Royals denied home field advantage against the Blue Jays in the 1985 ALCS?
This was actually a fairly tough on to dig up. As you mention in your question, the East and West swapped back and forth, and until 1985 the AL and NL were in sync. However something happened in 1985. Change came to the playoffs. The LCS were changed from 5 games to 7 and in addition the commissioner decided that the AL and NL would go to opposite divisions hosting each year. So in 1985 it was declared that the West would get home field as scheduled and that in the AL the East would get home field for a second year in a row. After that they returned to their regular schedules with the AL East hosting in odd years and the AL west hosting in even ones, and the NL east hosting in even years and the NL west hosting in odd years.
This was tough to track down, the best source I found was this mailbag from a Mets blog about the following year's NLCS.