Some of this may have to do with the quality of startups going in to the batch. As the reputation of YC rises, more and more good-quality startups want to join

Some of this may have to do with the quality of startups going in to the batch. As the reputation of YC rises, more and more good-quality startups want to join (rather than go on their own?). This of course doesn't take away the fact that YC has done a great job mentoring and helping early stage startups. This makes me think (not totally seriously, though) that a YC prep-school for startups might get a lot of attention. There seems to be some room for startups at an even earlier stage than YC would accept now.