Have you watched Butler and Graballo's Games? if not then try checking if back their last 3 games and you can compare how good they are in their own divisions .
let us not be blinded because of Donaire and Casimero's popularity instead lets look at what are their opponent capacity to face them and the possibilities of beating them.
I've checked both of Donaire's and Casimero's opponents and of the two Donaire will have a hard time figuring Graballo, he is young hungry, and undefeated, Donaire will dominate the early round and will try to knock him out just like he did to Oubaali, Graballo should pace the fight and do not be too aggressive it's the late-round where Donaire will expose his weakness, just like what happened on his match against Inoue.
It means that Donaire has all the tools to win against Gaballo even if the latter is young. Donaire will have too much experience for the young guy and he might be intimidated as well to fight Nonito. So I think Donaire will be too much, no disrespect to Gaballo, but they are not in the same league yet, he still need to get more fights at this level before he can pull an upset on Nonito.