He appeared at a Lucha Underground taping yesterday.
I haven't been much of a fan of Mysterio in recent years, but I'm kinda excited about this. He's a big star, so he can help bring more eyes to the product, which is a big deal. Lucha Underground still doesn't have a big audience, and if it gets a bit more popular and generates more buzz, they might have a better chance of landing a Season 3 and hopefully moving to a better network.
He's also a better worker than most of the lucha stars in the lockerroom. At this point he won't be able to keep up with many of them athletically, but there are a whole pile of wrestlers in Lucha Underground who have nothing going for them outside of athletic ability. There are guys there who can pull off amazing aerial feats but who haven't got a lick of psychology. I could see Rey being a great influence on some of those guys, and could really help out a lot of guys in the ring and make them better.
Plus in a more creative environment and on a taped show, I think he'll come off better than he has in WWE in recent years. It could be a much better vehicle for him as a performer. I could be proven wrong on this score, but I'm going to remain optimistic. Chavo Guerrero really got a new lease of life with the promotion, so I could see the same being true for Rey.