'Totals' in baseball betting can be awfully tricky, as there are a ton of factors that you have to take into consideration when betting on them.
The first thing to note is that the game has to go at least 8.5 innings for your 'total' bet to be recognized. Even if you have 'over' 8.5 runs and the game is 12-7 in the top of the 7th inning, if it starts to rain and the game gets called, your bet will be voided. The other note is that both of the starting pitchers that were listed must start the game. If either or both don't, your bet will also be voided.
The concept of a 'total' is simple. The 'total' is the total number of runs that both teams put up. It doesn't matter if one team does all of the scoring or if both teams end up going off and lighting up the scoreboard. A 10-0 game has the same 10 runs of a 6-4 game.
Often when you're looking at a 'total', you try to figure out how many runs the pitchers in the game will give up, not really how many the offense will put together. There is a huge difference between the New York Yankees trotting CC Sabathia and AJ Burnett out on the mound. Sabathia might have a 'total' of 6.5 in his game, while switching in Burnett instead of CC might cause the 'total' to jump to 8.5.
Now that you've got it, be sure to judge your overs and unders properly this year to cash in with baseball 'totals'!