Did you try with a calculated measure?
WITH
Member [Measures].[Ratio] AS (
[Measures].[wins.SUM],
[X].[ALL].[AllMember].[Apples],
[Y].[ALL].[AllMember].[Strawberries]
) / (
[Measures].[losses.SUM],
[Y].[ALL].[AllMember].[Strawberries]
)
SELECT NON EMPTY {
[Measures].[New Measure]
} ON COLUMNS
FROM [SomeCube]