Batista's contract with WWE has expired and he is a free agent. Batista claims TNA did make him an offer but with the large amount of money they have spent on bringing in other big names recently, they couldn't come close to matching what he had been earning in WWE. http://www.ewrestlingnews.com/stories/Huge_Batista_Update_-_TNA_Or_MMA_Debut_WWE_Re.shtml
TNA is a complete mess. I used to watch it on a regular basis up until Hogan and company came in and took over. I didn't think it was that good before, but it turned into 100% garbage. You'd think they'd be at least decent with some of the wrestlers they have now.