Internal Hiring: Slotting vs. Posting

Compared with slotted employees, workers who enter a job through posting have higher performance ratings, earn higher salaries, and are less likely to exit the firm.

Posting involves posting an open position and inviting candidates to apply. Slotting is basically appointing someone to the job. This study was conducted in a single firm in a single industry (healthcare), so the usual caveats apply. You can find the whole article in Administrative Science Quarterly.