''We determined that the key to dealing with a combat roller is completely based on timing. The key to stopping them while you're out in the open is watching the animation. You don't need to lock during the roll and you most definitely shouldn't be shooting. Literally watch the animation. I found it easiest to not attempt to lock on at all until their feet hit the ground towards the end of the roll. ''
''Now, I'll explain more about the second thing combat rollers are banking on. That you're already in or will predictably run for cover. The reason for this is that nailing the timing becomes substantially more difficult when you're firing from cover. ''
Some good information here OP, but there's an underlying issue that will make these methods difficult to perform consistently.
We're placed into lobbies with players from all around the world. Unless you're really fortunate (Unlikely), you won't be placed in a TDM where every single player is from the same region/country or with a super fast fibre optic broadband connection.
Now your post has clearly made it obvious that this method is dependent on strict timing within a narrow window to successfully counter a combat roller, however a majority of the time, due to the lag, the animation you will see of your opponent will differ from where their actual position will be due to the lag, therefore making this much harder to use, less useful than it could actually have been and ultimately still result in your death.