Those days when Kerala Express had an extra rake is long gone; now they're managing with 6 rakes. So diversion via ERN will only help improving punctuality of 12625/26.
Anyway, better to run both up & down Kerala Express via same station(ERN) than 12625 running via ERN & 12626 touching ERS as before. Now atleast there's no confusion: Kerala Express diverted via ERN!
Thanks to this avoidable loco change, the CC of 12625 too used to get changed on a daily basis.