tPA efficacy

When I was at the Sparrow hospital information session on strokes, I asked the neurologist presenter, What is the efficacy of tPA? The answer - tPA does not have an efficacy rating, it gives you a 33% better chance of recovery. That really means this implication that all the F.A.S.T. advertising is promoting about speed to hospital is wrong. A 33% better chance would be considered a failure in any normal business except baseball, it may be better than nothing but a business that depended on that would be overtaken by something better real soon. Why hasn't this happened in the stroke world?
I'm one of those failures of full recovery of tPA. Although it did allow me to survive and be a real pain in the ass.