Randazzo's book is entitled THE RISE AND FALL OF THE PRO-WRESTLING INDUSTRY.
The industry didn't really fall. I mean, even after Benoit's death, WWE had some pretty successful and banner years in terms of income and revenue. Sure the WWE and wrestling overall is not as popular as it was say in the late 90's, but WWE still has some of the best ratings year round for any cable network.
As far as the concussion thing, I don't think that's the only cause. Now definitely yes there seems to be an equating of head trauma and concussions to depression and manic depressive feelings that I can see. But I also don't buy the whole, "Benoit had the mind of an 80 year old man before his death." Benoit clearly hadn't lost any steps at all in the ring. He was still performing at peak really. And he sounded normal in interviews and pretty coherent. So he functioned a lot better than these "tests" seem to imply. I think it means there is just more to this than head trauma. I'd agree it was probably a combination of things that sent him over the edge. Be it the HGH/steroids abuse, he did have a DUI we never really heard about in 2003, and apparently he did have anger issues at home. I'm not saying any of this to absolve Benoit, I just can't completely buy that he had the head trauma of an 80 year old man because if he did I doubt he'd be able to function like he did.
However, I do think the business does need to change more beyond the wellness policies, drug testing, and such. I'm glad they are being more careful about chair shots and the like. But sometimes I think they are still overworking these guys way too much. Especially John Cena. Cena is getting older and now he's starting to deal with all these head and neck injuries despite the safety issues. These guys do need some more time off to rest. I know there's no off season or anything but WWE is too reliant on these guys some times.