Count/CountA counting wrong category

Hi, Anonymous 

Based on your description, I assume that you want to filter by player and get win% for each player. I created data to reproduce your scenario. The pbix file is attached in the end.

Table:

Names(a calculated table):

Names = 
DISTINCT(
    UNION(
        DISTINCT('Table'[Winner's Name]),
        DISTINCT('Table'[Loser's Name])
    )
)

You may create a measure as below.

Win % = 
var result = 
DIVIDE(
    COUNTROWS(
        FILTER(
            ALL('Table'),
            [Winner's Name]=SELECTEDVALUE(Names[Name])
        )
    ),
    COUNTROWS(
        FILTER(
            ALL('Table'),
            OR(
                [Winner's Name]=SELECTEDVALUE(Names[Name]),
                [Loser's Name]=SELECTEDVALUE(Names[Name])
            )
        )
    )
)
return
IF(
    ISBLANK(result),
    0,
    result
)

Result:

Best Regards

Allan

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