was Guillermo Rigondeaux a one hit wonder?

Because the opponents got smaller.

 

That is true on fighting bigger opponentsbut the effect on the fighter itself is still relevant on weight drain, not just the weight on fight might. We all know things chin, speed, endurance, are affected by how much weight was drained during camp. And some those (speed, endurance) do have an affect on power.

Again, might not make a difference on the outcome. But pure statistics does show Donaire’s performances at 118 were better there, and even stayed true at an older age.