The assumption is that Facebook is selecting the contracting agencies based on performance or cost. If Cognizant's performance doesn't meet the Facebook's standards they will get dropped, the same thing will happen Cognizant isn't competitive on price.
This downward pressure ends up directly impacting moderators. Cognizant needs to keep payroll costs low so they don't lose the contract, and the contracted accuracy target of 98% seems unrealistic. So moderators end up fearing for their jobs when they don't meet accuracy targets.