It's interesting to note that 20% of the companies have been working on their business for over a year (source: https://www.statwing.com/demos/yc-s12 ). Between that and the fact that YC is on record as looking for more clear-revenue companies, I think this shift will be more pronounced.
Another interesting note is that every major win (or apparent major win) for YC so far has had a very clear-- and very early-- revenue model (Dropbox, AirBnB, Heroku, OMGPop).
I think Reddit might have been more of a PR win than a major investment win. You might argue that it could have been the latter if the team had turned down the Conde Naste acquisition offer, but that might be the point. Without strong revenues it might not have been easy to turn down such an offer. I'm just speculating so please correct me if any of this is incorrect.
They sold six years ago when they were relatively tiny compared to today. There's no way they would have been a "major" win up there with the 4 huge exits webwright mentioned:
"We couldn't get them to tell us the acquisition price, but they did tell us that the company has raised just $100k (all in summer 2005) and currently has an average of 70,000 daily unique visitors and 700,000 or so page views."
Not to mention, it's arguably still not a win for Conde Nast - I know the founder of Reddit is seen as a success, sure, but the truth is it's hard to monetize their user base.
For what it's worth, stock in companies at these stages are often pretty damn liquid-- not quite as much as an IPO'd company, but still plenty liquid. YC could sell their stock in either company at or near their recent valuations on SecondMarket. For all we know, they could've partially cashed out in any of the rounds (though I'd bet they haven't).
Reddit was an early PR win. But, if you made a pie chart of returns for YC, Reddit would be a nearly invisible sliver. That said, it established a relationship with Alexis & Steve, one of whom is repping YC in the east and the other came back with Hipmunk, which just raised a huge pile of money in a huge space. So I think it WILL be a huge win for YC... But not from the Reddit exit.
Another interesting note is that every major win (or apparent major win) for YC so far has had a very clear-- and very early-- revenue model (Dropbox, AirBnB, Heroku, OMGPop).