No, two grand juries refused to indict. And that's way bigger than a DA not wanting to take on a case.
With grand juries, the prosecutors get to show them all the available evidence under the sun (even if it would not be admissible in court). They usually have direct testimony from some of the accusers as well. Then, you only need a majority of the jurors (not unanimous) that believe that there is "probable cause" (not beyond a reasonable doubt) that a crime occurred.
I'm not saying he's innocent, but if you can't meet that standard of proof, then what can be proven? He's been out a year already based on accusations alone. The fact that a court (civil or criminal) will never hear this case, then what is the NFL going to go off of?