Here's a refresher on the ASA Re-Entry Rule that was put in effect with the 2002 ASA Playing Rule Changes.
Rule 4, Sec 5 RE-ENTRY.
A. Any player may be substituted and re-entered once, providing players occupy the same batting positions whenever in the line-up.
B. Players may not re-enter a second time. The starting player and their substitute may not be in the line-up at the same time.
C. If a player re-enters the game a second time or a player re-enters the game in a position in the batting order other than their original starting or substitute position, this is considered an illegal re-entry.
EFFECT – Section A-C: Violation of the re-entry rule is considered an illegal player. The illegal player is disqualified. See Rule 4, Section 7 for additional penalties.
COMMENTS: To allow more participation in the game. This new ruling allows substitutes to re-enter. It was the feeling that if starting players could re-enter, then the substitute was penalized if he/she could not re-enter.