What is this graph trying to tell?

- - - Firm 3 Firm 2 Mo ! B Wage Firm 1 A 45 0 Mo Productivity (VMPL) FIGURE 15.15 The Wage Structure When Local Status Matters The higher the average productivity level of a firm, the lower a given worker's rank will be. Workers who choose high-ranked positions (A) must share some of their pay with their lower-ranked co-workers. Those who choose low-ranked positions (C) receive compensating payments from their co-workers