It's easy to disconnect the work from yourself if there are circumstances outside of yourself, like an unrealistic deadline. But your mood or level of experience (examples you gave) seem exactly the sort of thing that someone could use to blame themselves...
Kind of, but, my mood is not me.. I can be in a bad mood, I can be tired, there can be any number of reasons I'm not living up to my expectations of my normal output.. but that's still not _me_, it's part of the circumstance in which the work is done, and if it sucks, it sucks, doesn't make me suck any more or less.
I've done pretty decent stuff, I've done pretty silly mistakes. Thing is, that decent stuff, probably came at just the right time.. The silly mistakes, they probably seemed right at the moment, either due to some lack of information that I should have had, or something I simply hadn't learned yet.