If you’ve ever applied or thought of applying for a job via LinkedIn, you’ll know that the experience can be immediately disheartening: Openings that look interesting typically can see hundreds or thousands of applications in a matter of hours — data that LinkedIn, a social network for the world of work, proudly exposes in its own version of building up viral hype. But you may as well be throwing a penny into a giant fountain for luck to keep your application from drowning in that noise. Now Lin...