I played in a league last winter and if you played D, you played for the whole game. It's nice IMO. Some games you just bat and some games you play D & bat. Not like you play less innings, just don't substitute during the game. Makes the game go smooth. Substitute weekly, rather than during a game is my preference. Why go through the lineup twice and learn where guys hit, only to get yanked and have the next guy guessing? If you have two guys that play Right-center, why not play alternate each week? They can both always bat right? I really preferred it. Plus, it's kind of fun to sit there and just worry about batting while giving your teammates a hard time.