Apparently the win rates in EDT aren't that great any more. Someone posted a link to this effect a few lawsuits ago. The reason why people still file there is because the judges all now have good working knowledge of patent law and that makes trials fairly efficient. Dunno if this is actually true, but.
It really doesn't matter what the "win rate" is when it costs 1.5 Million and takes 3 years to win. The trolls have their offices there and they appear before the same judges every day. I have no doubt this makes trials fairly efficient for them.
A little fear in a court that if they start hearing a bunch of bogus patent cases and generally being troll friendly might make half the internet become inaccessible from their jurisdiction might not be a bad thing. Yes, that's pretty unfair to a lot of people, but unfair seems to be the currency of trade these days.
That ignores the selection effects. Once word of their reputation got out, people started settling the weaker cases rather than litigating in East Texas.
They also have helpful local rules, like the one that lets people file a cover sheet with the clerk a day early, getting a case number and priority. So even if you anticipate the lawsuit, you can't get out of EDT, as Cisco found out once upon a time.
