If you have seen Adam Garcia as Fiyero, then Oliver at 30% vocally is going to blow you away. LOL
As for being bored, Adam used to have conversations with the conductor whilst sitting in the class room scene, so again, whilst Oli has his off days just like any other human being, I have never seen him that unprofessional nor anywhere near as bored as Adam was at times either. :-)
It's funny, I had that conversation last night, I never appreciated Adam enough when he was there and always hoped he was off so I could see Oli. I'd still see Oli over Adam any day, but considering some of the understudies I have seen (bar Mark Evans), I would have Adam back any day over them, at least Adam was entertaining, plus quite pleasing on the eye.