It's about aerodynamics: if most of the wood is sticking out sideways, the arrow won't fly very well. However, if it all is behind the tip, then it'll at least have a chance to fly. Then again, extending the metaphor, you'll have one really long arrow, and that won't fly very well either.

It's not the best metaphor but it is a relatively well known and understood saying for many native English speakers (at least in North America).

I think some people who have replied to you are trying way too hard to make the metaphor fit. Top item later today will be about a Hacker Newsian with feathers, arrowheads, and a sharp edged rock, being arrested by Google's security while muttering about trajectories and wind resistance and trying to catch Googlers in the cafeteria.

I'd guess it's a mass thing. The more mass you have in the shaft of your arrow, the more momentum it has- ergo, the further it flies and the harder it strikes the target.

I think it's more like: we've got 1 ton of wood. Should we make one really big arrow, or a million smaller ones?

Yeah, if you read the article heading instead of just these misleading comments, it says "More wood behind fewer arrows". So it makes sense. It's about focus. More resources behind few projects.

A bigger arrow to hit a bigger target, perhaps? I don't know. I obviously intuit the metaphor, but it's sort of lost on me too.

Off to wikipedia...

Edit: Also, I should note that this tangential thread is why I love HN.

Maybe it's a momentum thing: an arrow with more wood would be heavier, and as a result it would create a greater impact.

Weird metaphor indeed.

more mass = more efficienty energy transfer from bow to arrow, better energy conservation in flight, and deeper target penetration.