About Brig SS- He is the Brigadier in command of 58th division.
Then Maj. Gen Jayasuriya was the overall commnder in Wanni-in command of ALL those divisions.
My personal opinion.
When you say ninth in line for command - it means that there are 8 other Major Generals-who are senior in age only to JJ.
A few would certainly be from support divisions-logistics-engineering etc-usually they dont get the Chief's job.
It leaves only guys in equal rank with longer service- from direct operations-which i reckon is far less than nine. then comes your achievements.
He commanded the biggest theatre- very successfully-silently .
If seniority isthe only criterion -that wouldnt serve the national interests. :))))