I wouldn't say he embarrassed himself, but he was embarrassed all the same. Because he got to show basically nothing (a tiny bit of jits defense). Two years of training isn't enough to be a top level MMA fighter, definitely, but he didn't really get to show anything he learned in those two years and I think it's pretty fair to call that embarrassing.
He wasn't able to show what he learned in those two year because he was shut down by someone who's been doing it for a long time and facing opponents of higher level in actual competition. If you trained for 2 years, without actually competing with anyone serious, would you be able to show what you learned playing a 1 on 1 basketball game with a NBA star? Would you be able to show what you learned after playing Street Fighter in training mode for two years vs an EVO veteran?
That's why I disagree. There's no way anyone could've expected more, including Punk himself. He was saying that lasting 30 seconds would be a victory for him already.
To make things clear, I'm not trying to find excuses. He lost and that's that. He shouldn't be where he was past Sunday in the first place, but, still, people are overthinking this too much.