def extract_v5_values(data):
    """
    Extract v5 values from a list of tuples.

    Parameters:
    data (list): List of tuples containing v5 values and other metrics.

    Returns:
    list: List of extracted v5 values.
    """
    return [t[0] for t in data]

# Example usage
data = [('v5_1768236144', 108217.11959687909, 721, 15009.3),
        ('v5_1768235312', 89435.63603047856, 734, 12184.7),
        ('v5_1768235983', 98379.19963352643, 987, 9967.5)]

print(extract_v5_values(data))