No not angry, but confused and disappointed. It happened to recently. A guy showed interest in me, asked me out on a date and then rejected me on the 3rd date. I was a bit mad because he wasted my time, but how was I supposed to know, right? He's just an immature dickhead, it's his loss and I dodged the bullet.
Happened to me once... I suppose it's my fault because I just saw something that wasn't really there. That's why I never trust myself about being objective when it comes to someone I like or am attracted to. Feelings, even the minor crush or attraction ones, distort my judgement and it's always best to seek advice from someone who is 100% detached from the situation and is able to see things as they are. This rarely includes friends and/or family, because 95% of the time they'll tell you that this guy/girl is interested in you whether it's the reality or not.
If I am viewing them as "under my league" then they should absolutely reject me.
Who would want to be with someone who looks at them like that? I wouldn't and I wouldn't want to do that to someone else. No one wants to be someone elses "safe bet". I think it would be best if you stopped looking at people by league and just got out there and want after what you want... what you really want, the person that you are really into not just the people you think will or 'should' say yes.
No I don't think I'd feel angry. Just confused I guess unless it seemed very clear that our differences were the reason. If that's the case, I could understand though maybe feel a bit disappointed for a while. Some incompatibilities do feel like red flags not worth pursuing.
I think there are a few problems with this question. someone "under your league" is subjective... and secondly, I its possible that you may have misjudged any "Interest" they might have shown, and thirdly just because someone is under your league, that doesn't mean they have to be attracted to you.