Paul's biggest advantages against the past MMA guys has been age, size and speed, all of which he'll have edges over Diaz on as well. He isn't technically great though, as Fury showed.
I think the reason he lost to Fury was Fury was faster than he was, and about the same natural size, so he couldn't weight bully and couldn't rely on just being too fast for an older guy. Fury just had a technically faster and more proficient jab, better movement and quicker reactions to the normal boxing stuff. Because he's been doing it longer, and athletically they're around the same stage.
What Diaz might have over the past MMA guys is staying power. Everybody knows he can take a lot of punishment. So maybe if he defends well he can get to a decision. A win is going to be a very tall order though.
That said, Paul is still raw, has definitely shown he doesn't like getting touched too much, and could gas himself out, so it's not impossible. From a technical standpoint Paul still makes a lot of mistakes. But is Diaz the type of fighter who typically takes advantage of the mistakes you see on film?
At 80% probability for Paul I think the price is about right currently