Sportsbooks have gotten tired of getting hammered by gamblers that took high priced favorites in baseball odds. The baseball betting lines were adjusted and taking high priced favorites became less popular.
Baseball odds not all that long ago would see the biggest favorite between -$200 and -$220 max. Those days are long gone, however, as favorites in baseball betting lines of over -$300 can happen now. A great example of how quality teams have often degenerated into overlays that have no value on the baseball betting lines would be the New York Yankees, who won 96 games in 2005 and made the playoffs and yet lost money for the season for gamblers that bet baseball odds.
If you could find three teams that are completely and totally over-valued each season on the baseball betting lines you would start with the Yankees and then include the Boston Red Sox and then the Chicago Cubs. In the case of the Red Sox and Yankees, you have the public going with the perception of these teams as excellent and perennial contenders in baseball odds. In the case of the Cubs, you have a large and national fan base that bets with their hearts instead of their heads in baseball odds.
In fact, with all three of these teams, you have the dynamic of them being pop culture icon type teams in which people that don't even know the basics of baseball odds will still wager on these teams due to name recognition and because it is “cool.” Along the same lines as teams that are now habitual overlays in baseball odds you also have the factor of starting pitchers, such as Jake Peavy and Johan Santana that are priced completely beyond what their actual merited baseball odds value should be.
Baseball odds, like all forms of sports odds, are all about value and you won't get any value in baseball odds by betting on power chalks and power pitchers.