Unless you're talking about something that can be objectively measured--widget output from an assembly line, average times to retrieve/place something in a ware

Unless you're talking about something that can be objectively measured--widget output from an assembly line, average times to retrieve/place something in a warehouse, and so on--the "complexity" you note is just fertile ground for gaming. It's downright trivial for an employer to massage "productivity" numbers in a way that supports their agenda.