They are supposedly going to split the time equally...but if one gets hot then they will probably be in more. Other injuries (e.g. Bell) may make it easier, but if everyone's on the same level, it will be an even split.
You may not know anything until the lineups are given to the ump, unless you have a good pre-game Phillies telecast to listen to.
The One, The Only, The Incomparable Mercer Boy.
blog (updated 6/21 - Pirates walkout.)