Player does not sit a tick...or does he?

[so cal lurker]

Originally Posted by BillyMac

Under what situation may a substitute legally enter the game without sitting a tick?

A player who has been replaced, or directed to leave the game, shall not re-enter (with rare exception) before the next opportunity to substitute after the clock has been started properly following his, or her, replacement. In other words, a player who has been replaced must sit a tick of the clock, however, a player doesn’t have to play a tick of the clock.

IIRC, if no other sub is available and a player can't continue. E.g., the team is down to 6 eligible players, the sub takes place, and before the "tick," a player is injured, blood is discovered on a player in the game, or a player fouls out or is ejected. The team doesn't have to play short.