I started wagering sports following Haralabos Voulgaris and his take on things was he mainly wagered only series in the nba. In baseball I think its an excellent idea, managers always mention the importance of winning a series and psychologically teams don't like to drop them it seems from the comments players make.
Its a great value if you have patience because if you lose a game like today with the cardinals or phillies[like the cardinals and phillies did yesterday] you are going to lay some serious juice,. You are going to lay juice on series wagers as well, but pitchers have off days and teams may drop a game but I dont think anyone sees philly dropping a home series to washington.