I am trying to insert data into a table using a stored procedure with one parameter. The parameter is looking for the name of a club. I want the SP to find all the players that belong to the club and insert them into the ClubNameTable. The problem is when I run the SP it inserts all the data from the join into the table, not just when the case expression is true.

CREATE PROCEDURE SSIS.usp_ClubNameTable 
    -- Add the parameters for the stored procedure here
    @NameOfClub nvarchar(200)
AS
BEGIN
    TRUNCATE TABLE SSIS.ClubNameTable;
    insert into ssis.ClubNameTable ([NameOfClub], [FirstName], [LastName])
        SELECT
            p.FirstName,
            COUNT(p.LastName) as 'Number of Last Names',                
            CASE
                WHEN @NameOfClub = 'Eagle Plate' THEN NameOfClub
                WHEN @NameOfClub = 'Atlanta United FC' THEN NameOfClub
                    ELSE 'Please choose either Eagle Plate or Atlanta United FC'
                end
    FROM [Location].Club as C
            JOIN [Location].ClubDetails as CD on c.ClubID = cd.ClubID
            JOIN [Player].Player as P on CD.PlayerID = P.PlayerID
            GROUP BY c.NameOfClub, p.FirstName, p.LastName
            ORDER BY p.LastName ASC
        declare 
        @RowCount int
            SET @RowCount = (SELECT COUNT(*) FROM Location.Club)
END
GO