As per your TT, DD overtakes MYS MAS SF and just trails in opposite direction.
MAS needs a non premium Mysore connection in morning hours. As of now 12609 is in the afternoon and Kaveri in the night. Similarly, MYS needs non premium afternoon connection to Chennai. 12610 in the morning and Kaveri in the night.
Also, DD in Mysore line has some technical issues. Cannot cover the distance in 2 hours.