I know someone that works in a sales oriented profession and who manages a large number of people. Their company is ruthless, you get only a couple of weeks to demonstrate you can hit the targets, and after that maybe a couple of weeks of grace after the hard talking to. Less than 50% of new hires make it through probation. Staff that survive all have the same attributes: excellent sales ability and focused determination. It also allows in a high percentage of narcissistic bastards though.
I don’t like the idea, but I wonder if a similar metric based probation would achieve the same in this industry. If you want people who can pump out quality content at a higher than average rate, set the bar high and cull ruthlessly during probation.