10 BY 10, going purely by your description, makes it sound to me along the lines of Malcolm Gladwell's pasta sauce realization[0]--if you want to find the perfect sauce for person X, you need to offer chunky, spicy, and "plain". None is inherently the best, so you offer three that are best in distinct ways.
I'm not familiar with the video and will check it out when I'm at home.
If I was to say more on 10 BY 10 it's that I don't see the differentiator. Plenty of search firms are staffed by people with domain knowledge and the pre-screening of resumes by an expert or qualifying candidate interest prior to resume submission are not significant enough to differentiate in that space.
If I was to be cynical, I'd say that going through YC gives them access to a lot of prospective clients because I fail to see why any particular significant investment would be needed to start a search firm.
I see the TC article talks about a marketplace so perhaps there is a development down the line of what their solution looks like.
[0] https://www.ted.com/talks/malcolm_gladwell_on_spaghetti_sauc...