THe point people are making is that Pacquiao is ranked higher p4p than COtto or MOsley, thus he should still be at an advantage or competitive with them at their own weightclass. If he wants the glory in beating them, then it should be done at their weight. If he fights them at a catch weight it is still impressive, but the arguement that they also had size on their side isn't as profound as if he faced them at their natural weight. I think Pacquiao shoudl still get a ton of credit if he beat Cotto at 146 or Mosley at 144-145, but not even close to what he would if he beat them at 147 even if they aren't better at 147 than they would be at 144-146.