Nate Diaz was able to pull off the much expected submission win against Melvin Guillard at UFC Fight Night 19.  However, it was a win that highlighted a lot flaws that Diaz needs to correct if he ever wants to become a major player in the UFC LW division.  Check it:

• Melvin Guillard was having his way with Nate Diaz prior to getting caught in that guillotine.  He out struck Diaz who enjoyed a huge reach advantage, and he was able to slip the majority of Diaz's punches as well.  Guillard beat himself in that fight IMO and with Diaz's length he shouldn't be getting out struck in such fashion.
• While Diaz has very good BJJ, he absolutely has no take down defense.  He simply can't rely on catching opponents in submissions as he moves up in competition because it's simply not going to
  work.
• Nate Diaz had trouble making the lightweight limit for the Guillard fight.  Rumor has it that Diaz may be moving up to the welterweight division(170lbs).  If that's the case, bullet #2 should be in bold because that division is full of wrestlers with good submission defense. 

Diaz is a very talented fighter.  He possesses something that  a lot of fighters don't have in that he has a pure fighting spirit just like his older brother Nick.  You simply can not teach that.  He's still very young and has time to make these improvements.  However, we've seen Diaz fight three times this year, and we haven't seen any improvements yet.  He got off to a slow start in each fight.  He showed poor take down defense in each fight.  He didn't use his striking/length effectively in any of the fights.  So if he ever expects to beat the top guys, he needs to get on the ball with his training.  Maybe it's time for him to branch out from the Cesar Gracie camp? 

UFC Fight Night 19: Diaz vs. Guillard coverage