Which supervisory evaluation style would you recommend the Executive Board use to evaluate the OPCO managers’ performance?

To answer this question, I would need more specific information about the context, such as the nature of the OPCO managers' work, the company's culture, and the Executive Board's goals. However, here are some general recommendations:

1. Balanced Scorecard Approach: This approach evaluates performance based on a mix of financial and non-financial measures, including customer satisfaction, internal processes, and the ability to innovate and learn. This can provide a more comprehensive view of performance than financial measures alone.

2. 360-Degree Feedback: This method involves collecting feedback from all directions: superiors, peers, subordinates, and even customers. This can provide a more rounded view of a manager's performance.

3. Management by Objectives (MBO): In this approach, the Executive Board and OPCO managers would set specific, measurable goals together. The managers' performance would then be evaluated based on their success in achieving these goals.

4. Behaviourally Anchored Rating Scales (BARS): This method involves rating performance based on specific behaviours that are tied to job success. This can help to ensure that evaluations are fair and objective.

Remember, the best evaluation style will depend on the specific circumstances of your company. It may be helpful to use a combination of these methods to get a full picture of the OPCO managers' performance.