I've wondered where he's been and it sounds like he took time off as a respite from the grind of the fight game. Arona claims to be fond of fighting in Japan, but he makes this curious statement about the cage and how the UFC rules fit his fighting style:

Sherdog.com: I read an interview where you said the UFC rules for made for you. Why do you believe that?
Arona: When I arrived at Carlson Gracie’s gym at 16 years old, I already wanted to fight in MMA, and one of my specialties was taking my opponent down, striking him and hurting him from that position. This was cut from MMA when I went to fight in Japan. In the UFC, you can use the cage, which is perfect for me, because once you have your opponent in the corner, there’s no escape; it’s excellent to use to get the takedown. Once on the ground, it’s perfect for striking; it’s fatal. With those rules, I guess the referee will have to stop a lot of my fights quickly, because my great strong point is striking from above, from any position. The third factor I see is that anyone in the ring who gets tired in five minutes is in the wrong place. I’m accustomed to fighting one 10-minute round and two five-minute rounds. In the UFC, it’s three five-minute rounds, which is like child’s play for me. I’m flying in and out with that time. I wouldn’t even stop to wipe my forehead. The UFC rules were made for me -- no doubt about it.

He is exaggerating the ease with which he could inflict his gameplan partly because there are overall better wrestlers in the UFC. That being said, Arona is more than a fantastic grappler; he's also a very good wrestler. In fact, he prefers guard passing from top control than the "typical" bottom game of some jiu-jitsu players. He's also enormous for the weight class.

There's no doubt the UFC light heavyweight class is already stacked to the brim, but the addition of Arona would be another worthwhile contribution. I'd love to see him fight Machida, rematch Rampage (I know, I'm just fantasizing here) or take on any number of other contenders. Here's to hoping the UFC can make it happen.