i dont know if 8 of them are wrong, but i do think some of them are inaccurate.
How i see things -
Georges St Pierre - The fight i see diaz getting his ass handed to him, with his tendency to like to fight on the bottom and a lack of head movement, i see him getting the worse on the feet and really battered on the bottom.
Fitch - I think fitch would probably take the decision due to staying on top, but i dont think as far as damage is concerned that Fitch wouldn't be able to impose his will too much on the ground. In the clinch i dont see fitch being able to batter Diaz like he would against alot of other welterweights, Diaz's clinch game and dirty boxing is often overlooked, hes really effective at that range. And on the feet at long to mid range Diaz would surely get the best of fitch in my opinion. I think Fitch would win a decision but i do think it would be boring with fitch playing it safe for the win.
Koscheck - with joshs tendency to stand up, and the way he likes to throw his punches, he could very well get picked apart on the feet. His trusty overhand right i dont see landing very often, and with diaz's ability to continue to throw and get in koschecks face the pressure would throw koscheck off his game. However koschecks bread and butter, his takedowns, are more then enough to take the fight to the ground. I cant think of a recent fight that showed if koschecks submission defense has improved, assuming it has i can see him winning a decision. I dont think his ground and pound will be much of a factor as diaz's constant sub attempts should force him on the defensive.
This is a fight i can see diaz winning if koscheck doesnt fight a smart fight, however if he does play it smart and keep diaz on bottom i can see him winning.
Swick - Im not sure how swick will react to a high volume high pressure fight, and whether or not hell be able to take 3 rounds at diaz's pace, since traditionally fighters with that build, who throw as much umph as swick does in his punches, tend to fade later on in fights where they are pushed. I think this would be a hot bout fight and im not sure who id take.
However, swick would not dominate Diaz on the ground as you mentioned.
Swicks reach advantage and explosiveness could cause problems for diaz if nick doesnt adjust quick, but i do see Diaz's chin being able to absorb more than swick can throw.
Thiago Alves - He murders nick stylistically, im not sure how long diaz's body would be able to hold up. The leg kicks take away his base and theres no chance of him putting alves on his back. I think it would be a brutal fight to watch.
Kampmann - Similarly to Condit i could see Diaz outworking him on the ground and making a disputable case as to whether or not Diaz won. On the feet he doesnt have the dynamic style of striking condit does, and diaz's striking defense has a bit to be desired against technical fighters who like to counter like kampmann does. I think Kampmann would do very well in this match-up. Kampmann's style is very technically sound and should make Diaz eat leather in order to dish it back out in alot of exchanges, he has the right style to keep diaz off of him. An accurate counter puncher who likes to operate at range.
Hughes - Right now with the layoff and the noticable deterioration of skills i think diaz would beat hughes, along with alot of other younger up and coming fighters.
Penn - Penn wins through samoan might and durability.
Karo - I personally think diaz won the first fight, and since that point i think diaz has improved more than Karo has. I think Diaz would beat him (again).
Hazellett - Diaz's bjj is good enough to nullify Hazellett's main strength, which is the ground game. On the feet its diaz all the way, i see this as an easy fight to pick.
Hopefully that rambling made sense