The evidence offered essentially breaks down to anonymous player reports (seemingly from a single bullpen), statistical cherrypicking, and the extreme unusualness of the Jay's 2010 offensive season. None of these on their own are convincing, but according to ESPN when put together they mean that "every pitch to a Blue Jay in Toronto is worth watching" which is of course meaningless pablum, but which again seems intended to implicate that the Jays are doing something illegal or unethical.
So are the Blue Jays stealing signs illegally? I have no honest idea. I'm sure they are relaying pitch location from second base with runners on; plenty of teams do that, and the Jays seems to be at the forefront of that. I'm willing to acknowledge that it's within the realm of possibility that the Jays are even going farther than that - not especially likely, but not completely improbably either. Mostly though, I think it's unfortunate that ESPN decided to run with what seems like at best a highly circumstantial set of allegations that are not backed up by it's own reporting. Let's review.