On his match with Inoue, he said that he's going to beat Inoue and that's what I think that he became overconfident on that time. That's just my opinion and if you think guys that it's not a sign that he's overconfident with those words, that's okay.
What do you expect Donaire to say, " I can't beat Inoue?" hehe.
Of course, he will say he's going to beat Inoue. It doesn't mean that he is overconfident but it's just the usual statement from any boxers to say that they are going to beat their opponent as was it's supposed to be.
If his statement includes, "Inoue can't harm me, Inoue is nothing, I can easily beat Inoue" we can consider him overconfident in that fight.