Look up definition of the word significant. It isn't a synonym for huge.
Like I said Matt Hughes is a better grappler than Diaz and GSP submitted him 6 years ago. He absolutely dominated BJ on ground. He didn't grapple with Shields because striking was a better route to victory.
Why exactly do you think Diaz is some great striker? He got dropped twice by Daley, lost 4/5 rounds to Condit, and was losing to BJ before he gassed.
Comparing two MMA fighters skills is always based on assumptions unless they've actually fought each other.
Both of their last fights were against the same guy. GSP won 5 rounds with a mixture of striking and grappling - Diaz lost 3 or 4 via striking.
Matt Hughes may have been a better wrestler and had better take downs than Diaz, but better over all grappler? That's debatable. Diaz has an excellent bottom game and has the better submissions. Let's not forget the fact that he's a Cesar Gracie black belt, not some Mcdojo blackbelt, where black belts are handed out like candy.
He didn't grapple with Shields and he struck with him instead. Did you watch that fight? GSP barely managed to out strike Jake Shields, one of the absolute worst strikers in the game today. The two of them put on an amateur display of striking, with GSP getting the edge and you want to try and convince me that GSP has a significant advantage in the striking department, when he's struggling with guys like Jake Shields on the feet.
He got dropped by Daley twice? And? Diaz gets dropped quite a lot because he throws no caution to the wind and is in your face firing off shots from the get go. You act like getting dropped by Daley, one of the hardest hitting and most technical strikers in the WW division is a crime. You don't seem to understand just how damn impressive that victory over Daley is. He gets dropped twice, proceeds to stand back up, drop his hands in Daleys face and tells him to hit him again "bitch". He then breaks Daleys will, and continues to knock him out in the first round. Can you name me any other fighters that have come close to KO'ing Daley like that in his career? There are absolutely none. No offense, but you just don't seem to be very good at evaluating a fighters skill set, either that, or you're incredibly biased towards wrestlers and GSP, I haven't quite worked it out yet.
He lost 4/5 rounds to Condit? On what god damn score card is that? And no, GSP didn't win against Condit with a mixture of striking and grappling, he won that fight through 75 percent grappling and take downs/smother top control, and the minority of the fight was spent on the feet, where Condit dropped him to the floor with a head kick. The same head kick that Nick casually sneezed after and wiped his face when Condit landed it on him.
As for the folk saying what elite strikers has Diaz beat, weren't the same anti-Anderson Silva fans demanding to know what great strikers Silva had beaten before he fought Vitor Belfort?
He's out boxed and KO'd arguably the best striker in the WW division in Paul Daley, he made BJ Penns boxing look flat out silly (the same guy Freddie Roach called the best boxer in MMA), he's out boxed a decent boxer with a professional boxing record under his belt in KJ Noons, he destroyed Takanori Gomi when Gomi was KO'ing fools left right and centre during the peak of his career in Pride, and had some of the best body shots in the game back then.
Has he beaten some of the most elite strikers at WW? Well, who are al of these elite strikers in that weight class? There really aren't many in the division, the same applies to Anderson Silva in the MW division, how many elite strikers has Andy beaten? Not many, yet it's quite obvious to see he's a jedi in the striking department. The same way it's obvious to see that Diaz is a beast of a boxer in the WW division.