Let’s look at some examples of baseball odds totals.
Baseball odds totals are based on money lines. For example, if you see a line that says “Baltimore Orioles +$130, Detroit Tigers -$150, 10.5” that number “10.5” would be the total that you would bet over or under on in baseball odds. If Detroit beat Baltimore 5-4, the combined total would be 9 and the game would be considered an “under” in baseball odds. If Detroit beat Baltimore 6-5, the combined score would be 11 and the game would be considered an “over” in baseball odds.
One of the advantages to playing totals, and why so many professional gamblers that look at baseball betting lines prefer over/under betting, is because the baseball betting lines are more close to even money, generally at -$110 to $-130. Compare that to baseball odds on sides where quality favorites are nowadays pushing over -$200 and you can see why many professional gamblers like totals in baseball odds.
Another factor that goes into baseball odds and totals is pitching. Quality starting pitchers on quality teams are at an all time high as far as the baseball odds are concerned but you can still get a price on such pitchers by betting the “under” where you don't have to lay out well in excess of -$200 or more like you would have to on a side wager. By the same token, when a couple of bad pitchers on good hitting teams matchup, it is a far better value to just bet the “over” in baseball betting lines than to potentially have to lay out big money on the chalks.
Over the years the oddsmakers have really cracked down on “playing favorites” and are charging high baseball odds for quality home teams. Betting totals is a great way to get around all of that and not break the bank on overlays.