It sucked horribly when Big Nog lost to Mir both times but other than that one, the only real losses that really bothered me much was when James McSweeney got eliminated from TUF Heavyweights (I trained with him) and when Rashad Evans lost to Jon Jones as I thought he had a real shot of beating him. I've predicted quite a few fights wrong but those are the only real ones I can recall bothering me. On the otherhand, I do get disappointed when I think a fight is going to be close or a good fight and it isn't
