WITH current_senior_employees AS (
    ...
),
performance_last_5years AS (
    ...
)
SELECT
    ARBITRARY(first_name), 
    ARBITRARY(last_name), 
    ARBITRARY(email),    
    SUM(num_of_managed_employees) AS total_num_managed_employees,
    SUM(num_of_managed_projects) AS total_num_of_managed_projects,
    SUM(revenue_generated_by_managed_projects) AS total_revenue
FROM current_senior_employees
LEFT JOIN avg_performance_last_5years
ON id = employee_id
GROUP BY employee_id