should the fight happen right after the GSP fight (i.e. about right now) I think Diaz experience wins him this bout. Rory is young and green. The 1st round would be the hardest for Diaz, but body shots will eventually end up eating Rory's gas tank, the 2nd would be even and the 3rd would see nick dominating in the stand up and rory reluctant on TDs.
it would be a fun and entertaining match up for sure, possibly ending in a controversial split decision for a 3 rounder, but I see Diaz winning a main event/5 rounder agains rory anyday of the week and twice on sundays.
and I'm far from being a diaz fan (tho his attitude and words at the pre fight conference definitely made me respect him more)