Mir has beat some quality opponents but he's been owned by lesser opponents. The trait his opponents had in his big name wins was a weakness in submission defense. There's just not a lot big wins on his resume at all.
He was absolutely owned by Pe de Pano, likely 205 Vera and 205 Ian Freeman. You have to think if Cruz could destroy him as he did, Minotauro would also have his way with Mir.
Conversely, no one without a huge name in the sport has beat Nogueira. His wins read like a who's who of the sport.
On top of that, I haven't seen a more likeable fighter than Nogueira. I have always admired his skill, but he's made a life-long fan of me on the basis of his overall decency. I hope Rodrigo stomps the proverbial mudhole in Mir's arse.