This fight seems to me to be easy to analyze, but difficult to know what will actually happen in the fight.
I believe Swick has the better hands. He has the faster hands, and a sizable reach edge. The power is fairly equaly. If Swick can stop the takedown, I expect him to win. As for the takedown, Riggs has not demonstrated anything spectacular at getting takedowns, although he is certainly capable. It is hard to judge Swick's ability to avoid the takedown, because he is basically untested. I do like what I briefly saw against Vignealt.
On the other hand, if Riggs is able to get the takedown in a consistent fashion, he will likely beat the living shit out of Swick. I don't think Swick is slick enough with jiu-jitsu to catch Riggs. Let's face reality, you do not want to be on the bottom of Riggs. He ranks up there with Fedor as far as the kind of power he can generate from within someones guard (pound for pound that is).
I have made great money betting Riggs in the past, but don't feel confident in which area the fight will be fought in (ground or standing). Maybe someone knows, but I don't.
A couple other factors, Swick is supposed to be in phenomenal cardio shape. No matter how Riggs looks, he seems to not have the deepest gas tank. One other thing that is worth mentioning is that Zuffa would not have booked this fight, if they expected Swick to lose. They seem to really like Swick, and want to market him. Additionally, Swick is very untested, while Riggs is one of those fighter with deep experience.