I am a huge Nate Diaz fan and the first to admit Nate is the easiest fight for Conor out of the available pool of fighters. It's not even close.
Ferguson, Khabib and Alvarez are all far worse matchups for him and two of those three are actively preparing for a fight.
If you follow Nate on Instagram or Facebook you know he hasn't sparred since December. He took January off and was on vacation and teaching some seminars. He went to Hawaii as well (you can see photos of him and BJ Penn releasing the new shirt Nate has on Penn's label)
Nate is the least dangerous matchup and literally coming off the couch.
This got booked because Conor wanted the biggest payday with the easiest match. It is as simple as that. You cannot hold it against him because RDA was the toughest fight and that is who he signed for, but RDA didn't make it.
Expect a far worse Nate Diaz in the Octagon than we saw in December. On the upside, he's getting a huge payday.