On a side note: I had no idea YC teams were this competitive with each other. I still had the image of one big Nerd Summer Camp that happened to spit out companies and connections. This makes it sound more like the Skull and Bones guys competing to meet the President at Secret Meeting X.
As far as I've seen, they are not (and, neither of these teams is a YC team...they are YC applicants, along with 400+ other teams). The teams tend to be very well-equipped coming into the game and don't really feel the need to break up other teams before they've had a run at it. When a couple of companies fizzled out after the program, I suspect there was a bit of competition for who would get some of the folks from those no longer existent companies, but I'm sure it was friendly (at least I can't imagine any way it could have been otherwise...everybody is still friendly at the events). Others started working on new ideas of their own rather than joining an existing YC company.
Anyway, I think it's a poorly executed attempt at being unethical. If you had a friendship with the person who tried to poach, that person should have realized that he was going to dagger your relationship by trying to steal your partner without even pitching an idea.
Given that your partner is very tight with you (and apparently barely knows the poacher), obviously the incident was going to get back to you . . . one would have expected that the poacher would have tried to partner with you guys or, at the very least, have made a damn compelling argument for why your partner would ditch you.
If you're gonna be shady, you've gotta be strategic about it at least. LOL
This is Arthur Anderson thinking, not Y Combinator thinking.
If you jumped on one of my best people "in an instant", then you better be prepared to set aside resources to deal with me. Are you sure you really want to do that?
But whenever someone comes to work with/for you they're likely precluded for working for/with someone else. Sure there could be reasons not to try and poach someone, but in general I don't think you are responsible for the person/company left behind.
View my response here: http://news.ycombinator.com/item?id=62109
I'm assuming since you are applying for funding from YC that you are looking to start a company (YC acceptance or not). If that is the case, you should be glad that you weeded out someone weak while it is easy and not later on down the road. This could be a valuable lesson: Choose who you work with and trust very carefully!
If this guy can get up and jet on you this easily, think what would have happened after you actually started and financial and emotional stress enters the equation?
My advice is go find someone who you can really trust as a co-founder. Someone you know you can depend on when the going gets tough.
That's not for you to decide. If what they did was unethical, then you have a responsibility to share. If it wasn't, then anything you say won't matter anyway.
I place ethics more important than anything else when considering partners. WAY more important that skill, work ethic, or connections. Take it from someone who has been burned more than once by lying, cheating, stealing, and backroom deals that my partners thought were "no big deal". F*ck 'em. They'll never get a second chance with me. Never.
You're probably tempted to say nothing so you don't offend. Don't. Spare the rest of the community the same potential headache and tell the whole story.
(Personally, if someone tried to poach my partner, only one of us would leave the room alive. This isn't a game anymore.)