Betting on your favorite teams or players in the case of some propositions is one of the biggest traps that amateur bettors fall into when betting sports. Sure, we can understand the appeal of betting on your favorite team, kicking back and rooting them on, but if you’re trying to win money at sports betting, this is far from optimal. Not only is wagering disproportionally on your favorite teams a –EV decision, but it’s also an area where bettors are missing an important edge because of their bias.
Imagine a football match between Team A and Team B. A sports betting agency offers the odds 1.8 for the victory of the home team (A). If we suppose a 10% margin of the betting agency then (according to its bookmaker) it represents 50% (or 0.5) winning chance of the Team A. How do we arrive at this value? The procedure to determine the odds and winning chances is described at the page Sportsbook odds calculation (clear examples are included). It will be partly obvious from the further text too.
There are other things too, but those are the key things you need to deal with. So the bookie makes money by adding the gains from knowing the odds better to the gains from being paid the vig. The way you’re going to make money is by making sure that the losses from paying the vig are less than the gains from knowing the odds better. It’s just maths.
The rule against gambling in baseball is known as "Rule 21," which is publicly posted on dugout walls and states: "Any player, umpire, or club or league official or employee, who shall bet any sum whatsoever on any baseball game in connection with which the bettor has a duty to perform shall be declared permanently ineligible." People permanently banned from Major League Baseball are also forever banned from entry into the Baseball Hall of Fame, although most such people have been reinstated a few years later by a later Commissioner of Baseball. For instance, Mickey Mantle and Willie Mays were both banned from baseball in 1983 after taking jobs as casino greeters (which would have expelled them from the Hall of Fame had it been allowed to stand); they were reinstated two years later. Only Rose has yet to be reinstated.
ATS equals “against the spread”. The spread is the number oddsmakers use to give people other betting options besides only wins and losses. A spread for a Premier League fixture would be something like .5 or 1.5. One club would need to lose the match by no more than 1 or 2 goals or the other needs to win by 1, 2or more goals. If the final score doesn’t reflect the number set by the oddsmakers, your bet won’t cover the spread and you can’t win your bet.