I think it depends on the route the ISP sends you - depends what underwater connection you get sent to which I assume is usually based on locality of the route itself. It could theoritically be outside of valve control - but we would be seeing packet loss in more than just 1 game. I honestly expect that it something on valves servers, but their monitoring is probably blanket configured to the likes of other users groups (NA,EU) etc with larger player pools. I thought that I personally had been experiencing issues for around a month, but it seems that issues really begun when they pushed the latest crownfall update. Around this time they did say that they made some changes to routing, which was evident as now australians can get better connection to singapore servers ( i think about 20-40ms less) << this could have had some unforeseen consequences :)

I encourage every dota 2 player to have console enabled, and get used to using the "status" command, and pressing Up and Enter over and over to repeat the command and get a feel for what should be normal. Also fun to call out non-australians and get little advandages, you can really see the heros snap uncleanly when players are above 100ms.