Wanted to create a composite score for performance evaluation for each individual project each of my team-mates undertakes. I was thinking a mixture of complexity score and performance rating ( per project), and multiplying both of the them. My rationale was to accentuate any specific aspect which overperforms or underperforms to shine out.

The resulting score can be visualized on a histogram and possibly central 2sigma values can be given an average rating, the next 2sigma can be given slightly more extreme ratings and the remaining can be given the highest/lowest rating accordingly. Do you think this should work. Scale for complexity score and performance rating will be 1-5 for each? Is there a scientific method to go about this. Share your thoughts!