Yes, Nick Diaz (25-7) is riding a 10-fight win streak against fighters who total a win/loss record of 201-101 and that is inflated with wins over fighters well past their primes: Hayato Sakurai (35 wins)—who was considering retirement—and Frank Shamrock (23 wins), who came out of retirement to fight. Of all those fighters, you will not find a single fighter in the current top 25 either. Matter of fact, it is rare that Diaz scores a win over a fighter ranked in the top 25.
Diaz has amazingly never defeated a fighter ranked inside of the top 10 and has been defeated every time he has tried.
The sad part is that Nick Diaz does have excellent skills, but fans rarely get to see them on display against an opponent on, near or above his level.
Diaz's biggest wins are over Robbie Lawler, KJ Noons and Paul Daley. Don't forget Hayato Sakurai and Frank Shamrock...if you want to include them as relevant wins. He also beat Chris Lytle by split decision in 2002 when Lytle was 9-6-5, if you want to try to help Diaz's cause.
I find it difficult to rank him ahead of fighters who compete in relevant fights and against top competition as I find Nick Diaz to be the biggest fraud in MMA and the most over-ranked fighter in the world.