The author of that article, James Bessen has been called out on questionable methods or analysis in some of his studies. For instance, he's the guy who created the "trolls cost 29 billion" meme out of thin air, the debunking of which [1, 2] never got much press.

Here's a study that directly refutes the claims article from another researcher with a lot more data:

http://papers.ssrn.com/sol3/papers.cfm?abstract_id=1597919

It finds that Eastern District of Texas is not even in the top 5 when it comes to plaintiff win rates.

1. http://papers.ssrn.com/sol3/papers.cfm?abstract_id=2117421

2. http://blog.patentology.com.au/2012/06/29-billion-us-troll-t...