In order to make sure that one position doesn't get overly favored during the drafting process (e.g., picking five bench quarterbacks in a league that uses only one starting quarterback), the autopick algorithm uses a simple ratio that determines bench depth for each position based on the number of starters your league uses. So, the more starters you have per position the deeper your bench is for that position.

So, if your league uses one starting quarterback, one starting running back, one starting kicker, and three starting wide receivers, your bench contains up to three times as many wide receivers as kickers, running backs, or quarterbacks.