Yeah, if you are on the chicago blizz datacenter.. your likely going to run into these issues.
Can Rogers do something? Maybe.
It would require PATHING changes.. could those be done? Possibly..
It would depend on what other peering partners they have in the area, etc...
With chicago being not THAT far away from Ontario... there likely isnt that many paths to choose from.
Blizz has been collecting alot of data the last few days from people... Really, it something that AT&T has to fix and blizz is working with them.
Blizzards datacenters are all on AT&T backbones.. so in the end, has to go through AT&T one way or the other at least at the end.