Paul Graham, a partner at Y Combinator a successful Silicon Valley incubator, writes that he has found a key sign of future success among the startups that are recruited into YC's twice-yearly mentoring programs.

What is this indicator?

I noticed a pattern in the least successful startups we'd funded: they all seemed hard to talk to. It felt as if there was some kind of wall between us. I could never quite tell if they understood what I was saying.

The successful startups didn't need to be told more than once.

The startups that do best are fire-and-forget in the sense that all you have to do is give them a lead, and they'll close it, whatever type of lead it is.

... the most immediate evidence I had that something was amiss was that I couldn't talk to them.

Has Mr Graham truly found a way to identify failing startups? -- or has he merely discovered a problem with his communications abilities? And isn't this then a flaw in Y Combinator's raison d'être? That it can't teach startups to do what they need to do?

After all, the founders that get it would probably do well anyway -- it's the others that need the help that Y Combinator says it provides.