From outside it feels like YC is becoming a frat house. I think it will help if YC steps out and brings in some unusual partners.
Of course it's easier said than done. If you're busy running YC it's hard to have the occasion to meet and find people who are not part of the same frat house.
Paul Buchheit and Geoff Ralston never had YC companies and first became well known creating major advancements in email. Trevor Blackwell is a hardware engineer who spends his time building segways. Carolynn Levy is a lawyer. Robert Morris is an academic. Kirsty Nathoo is an accountant with an engineering degree who went to school in the UK. Jessica Livingston has an English degree and is best known as an author who wrote about primarily non-YC founders. Garry Tan is well known for his design expertise. PG has a philosophy degree, spent time in painting school, and has a PhD in CS. That's a pretty diverse group. The fact that the last 3 full time partners they brought on are young YC founders is pretty much meaningless - why would they not bring on the people they have worked with before? It just so happens that recently, most of their work has been done with YC founders. Honestly curious - after reading the bios of all the partners, how would you suggest they bring on more "unusual" partners? Any examples?
I wish everyone from Google, Facebook to YC followed the model CRV has been using [1], "Each member votes on a scale of one to four how confident they are in the investment, with one being least confident and 4 being highly confident. A majority of votes in either the least or most confident category is considered a troubling sign."
I think the issue with YC now is a bottom up issue. It's hard to bring outside partners if you have no working experience with them. Those that you can work with, are mostly YC alums who were vetted through the YC culling process which often breeds the same people.
So YC might want to use a similar approach as CRV. If everyone is so confident about a team then maybe they are picking the same old people. In contrast if there is a strong dispute, that might be a good sign.
At least you bring diversity and maybe some unusual bets into the YC and ultimately in 4-5 years end up with a more diverse group of partners.
That being said, this might mean a big change in the application process, as the current early round filtering process by the alums will most likely eliminate diversity.
Of course it's easier said than done. If you're busy running YC it's hard to have the occasion to meet and find people who are not part of the same frat house.