I also guessed the same. Then I also imagined that for shunting purpose WDG4 will not require. Then I again imagined that suppose BAY-UBL and TNGL-RNJP line gets electrified. Then to bring freight from JSW e loco will be not possible so to bring and stationing at Ballari or Tornagallu Jn those WDG4 may require so that the remaining would haul by e loco.