Malpractice premiums did drop, as one might expect them to. In fact they have gone down in most, if not all, of the states that have enacted tort reform. But what I said is that there is no evidence that tort reform has resulted in a reduction in healthcare insurance premiums or healthcare costs. And the link you provided makes no claims that it has, in Texas or anywhere else.
But, the article provides evidence that the reform increased access to healthcare by attracting medical doctors to Texas, as well as expanding charitable expenditures by non-profits that no longer had to spend the money on malpractice premiums and lawsuits.
I think that's a winning combination.