Over the weekend the Yankees beat Dellin Betances in arbitration and will pay him $3M this season instead of the $5M he was seeking. That $3M represents a record salary for a setup man in his first year of arbitration. No other setup man received even $2M as far as I can tell. That $5M Betances and his camp were requested is closer money.
The arbitration system, which has been around since 1974, is pretty old-fashioned. From what I understand there are a list of approved statistics each side can use to state their case, and for relievers like Betances, there is no more valuable stat than saves.