Regular Season: As a mercy rule is used and other factors affect the length of a game, a starter may be replaced after three(3) complete innings, but not before. Half game players must be inserted no later than the beginning of the fifth inning. A player may be substituted at any time due to illness or injury. No half game player will play more than four(4) complete innings in an eight(8) inning game, unless he replaced an ill or injured player. A starter removed without completing four(4) complete innings due to illness or injury may reenter the game but not before his replacement has played four(4) complete innings. As we cannot guarantee the length of a regular season game the second half players will not be guaranteed neither three(3) nor four(4) complete innings. The manager should make every effort to balance first and second half starts.
Not bad but it does limit the creativity of managers and teams to have more players play more time. Let us consider if a team has eleven guys for any given game. What if after two innings two starters are subbed for. After two more innings the starters return and play the remaining
(potentially) six. Two more starters sit for two and the original subs move over to their batting spots. Then after two more innings the second set of starters return and two more starters sit the last two moving the two subs into their spots. Eight guys play six innings instead of four playings four each. Works even better if only one sub. CAN'T do this under this rule. More often than not we have one or two subs only. Think this rule as written is limiting.