We set this page up at the beginning of Season 20 when crabman26 lost a player to Rule 5 that he had just traded for ("the crabman rule"). The idea is to have one reference page for obscure rules, procedures and general oddball HBD shit.
When are players subject to a demotion penalty, and when are they not?
The only time players are not subject to the demotion penalty is preseason - from the cycle after budgets are set to roster freeze day. After that, the season has started and you risk a penalty when you demote. There is a common misperception that demotion penalties are not in effect once ML playoffs have started. I assure you from personal experience that demotion penalties DO apply during the playoffs.
RULE 5 DRAFT
Traded Player Gets Exposed To Rule 5 Draft (crabman rule):
Players involved in trades that complete within 24 hours of the roster freeze are not exposed to the Rule 5. crabman's trade completed more than 24 hours before the roster freeze, and he was away from his computer and unable to add the player to the 40, so the player went into the Rule 5.
What happens if a player is currently involved in a trade offer or on the waiver wire and is selected in the Rule 5 Draft?
If selected in the Rule 5 Draft, any outstanding trade offer involving
the player is automatically canceled. If the drafted player is on the
waiver wire, any pending claims are canceled and the player is also
removed from the waiver wire.
How many games do you have to wait at the beginning of the season before promoting a minor leaguer to the majors so that he doesn't accrue a year of ML service time that season?
It's actually 20 minor league days. See the complete rule on how service time works at Admin Office > Help > FAQ, then scroll down to Players, How Does A Player Gain Big League Years Of Experiece?