def extract_key_stats(data):
    """
    Extract key statistics from a list of tuples.

    Args:
        data (list): List of tuples containing v5_id, value, and other metrics.

    Returns:
        dict: Dictionary with 'max_value', 'avg_value', 'min_value', and 'count' keys.
    """
    stats = {
        'max_value': max(value for _, value, *_ in data),
        'avg_value': sum(value for _, value, *_ in data) / len(data)
    }
    return stats

# 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_key_stats(data))