If you need to add a new trader to your team, what do you do? One response would be to ask around, talk to the people you know, hire when the opportunity arises (even if that doesn't necessarily coincide with the need). Larger firms will typically outsource the problem to a headhunter. In a very large firm, the dependence on a set recruitment process will not necessarily take account of the distinctive needs of the individual trading desk.
Both approaches - word of mouth, leaving it to the headhunter - can be problematic. If you limit the field to known and referred contacts, you may not be gaining exposure to all the available talent. But if you dump the problem in the lap of a headhunter, you're effectively outsourcing the future cohesion of your team, not to mention your future trading performance, to somebody who probably wouldn't be able to tell you the difference between VWAP and the sound of a fly-swat in action.
There's a third way. Martin Gymer, who has been running FX options desks for long enough to know who's good, who's bad and who would blow all your fuses, has evolved a new approach to talent-scouting. It sounds simple, but it isn't simple: set a trader to find a trader.