You need to interview someone in their 25-30's. Anything under that and you're looking at an entirely different mindset. What college major did the 2 individuals have?
In order of importance: Nice person. Smart. Knows stats. Can program. That's probably it. Everything else can be fixed or learned. I mean, this is not my first rodeo (if anything probably my last one). I know that I'll have to kiss a lot of frogs to find that one prince, but it's been one regular frog-kissing festival so far.
Someone who is 30+ will likeley be too senior for this position. It's a junior role, there is a lot of scat work involved. Math for the first one, second had masters in CS.
You need someone to fill orders according to your models? I think I would be an ideal candidate. You can be assured that your trade secrets are safe with me once you evaluate my employability profile. Hedge funds probably won't give me the time of day. But, I can make a case why you would want me. Please ask Bob: "What is this guy doing?" If interested, we can do a Skype conference from there. Stop wasting your time with fresh grads with their thoughts in the clouds fantasizing about what high finance should be. This horse is broken in.