You should also take into account the current form of each team's bullpen. Are they any good? Is the closer/set up man available for that day's game? Are there specific match ups that favor one team over the other that might come into play in that game (i.e. a reliever owning a specific batter that might be up in the late innings with runners in scoring position).
It sucks when you lose a game due to the ineptitude of the bullpen. Of course you could always just bet the five inning line and take the bullpens out of the equation