I saw that, TS ( ͡° ͜ʖ ͡°)
Probably very good based on credentials of the guys he rolls with (Nick, Jake, Kron, etc). In his division though Nate isn't one of the biggest/strongest so if it goes to the floor he's not very likely to transition/reverse to top control. Plus the Diaz brothers rarely go for take downs where they could transition from top control in someone's half or full guard. I've seen a few judo tosses from them here and there but they otherwise like to stand and bang.
Nate's more of a power bottom.
Here is some great top game...His guard is fantastic but I can't recall seeing him spend much time on top?