It’s a lot different than it used to be and it’s a lot harder to figure out. You’ll see the starting pitchers and you’ll be able to decide the hurler you want to go with. Research the average innings he lasts in his starts. You might want to look to see how many pitches he threw in his previous start and if it’s more than 100 (usual pitch count limit for starters) he might not last his average in this outing. The best thing that can happen, is your starter goes far into the game. Because, the starting pitcher is the only pitcher you’re sure is going to pitch, the rest becomes somewhat unknown. You’ll need to take a look at the bullpen and see how effective the relievers have been. Have they been overworked? This becomes a factor, especially late in the season.
Overused relievers will often wear down. MLB.com has stats on every team. Take a look at the ERA (earned run average) of the team's bullpens. It’s not an exact science, because you don’t have any idea of which relievers will be used. The manager might decide to use just one or two or the entire bullpen.