The general rule regarding parlays is: DON'T.
Parlays generally carry an increased house edge than straight bets, therefore you give the book a bigger advantage over you once you play them. That, by itself, is reason enough to suppress the misplaced feelings of greed coupled with fear that often result in betting parlays. People think they're risking less with parlays, however they are not. They believe they can win more with parlays, however they cannot. The bigger win with parlays is far outweighed by the higher probability of losing. Parlay bettors are actually risking more, with less possibility of collecting.
A parlay is not an individual bet. It is two bets -- a one-unit bet on one team and a two-unit bet on the other. Which team gets the two-unit bet? In point-spread betting at constant money odds, if both teams win or both teams lose it doesn't matter which team gets the double bet. When one team wins and one team loses, however, the double bet is presumed to have been on the loser. How smart is that for the bettor? Go ahead, create a parlay. We'll wait until both games are over, and in case of a split we'll put the double bet on the loser. If your bookmaker sold you a parlay with that line, how many of you would still make the bet?
A parlay can be bad money management. In a parlay you either bet double on the second team, or nothing on that same team, depending upon whether the first game won or lost. That adds an element of luck to your betting that doesn't should be there. The skilled handicapper is definitely wanting to make smart investments. He tries to eliminate the effect of luck to the greatest extent possible to make his results as predictable as you possibly can.
As with every rule, however, you can find exceptions. The exception to the rule regarding parlays occurs once the two bets are co-dependent.
I knew one bookmaker who was simply taken for tens of thousands because he didn't understand the co-dependency of certain bets. He allowed a player to consistently parlay the first half with the overall game. The ball player parlayed totals by combining the over in the first half with the over in the overall game, and the under in the initial half with under in the overall game. Both parlays were manufactured in the same game. Each and every time the player won he would win 2.6 times his bet. Betting $100 on each parlay, if one of them won, the player would win $260 and lose $100 on another parlay for a net win of $160. He could never win both parlays. If he lost both parlays he'd lose $200.
Initially, this were a great chance of the book. The normal coin-flip probability of winning one parlay out of the two are 50-50. So far as the bookie was concerned the bettor ought to be winning $160 half enough time, and losing $200 half the time. The bettor, however, making $500 parlays, was ahead more than $20,000 after 6 months, and the book begun to look at what the bettor was doing more carefully.
The problem for the bookmaker was that the two halves of each parlay were co-dependent. At the end of the first half, the bettor was almost never in a 50-50 situation.
Take the Thursday night game between Utah and Air Force. The overall game total was 53 and the first half total was 27. At the end of the first half, the score was 31-21, for a complete of 52 first-half points. The initial half of one of many parlays, the "over" in the first half was successful. For the parlay probability to be correct, there should now be considered a 50-50 probability of winning the "over" for the overall game. Obviously the chances of winning the "over" in the game were not 50-50 but better than 99% and only the "over." The ball player only needed to win the first half of the parlay to be virtually assured he would collect 2.6 times his money rather than just $10 for $11.
Before you rush out to try this, be aware that most off-shore books are far too smart to allow you to parlay first half to game. If they do let you do this, start worrying about collecting because that book will be taken up to the cleaners.
You can find, however, some less obvious co-dependent parlays that can still be made at many books. One type of co-dependent parlay may be the parlay of the side and total in the same game.
Any game in which the total is significantly less than double the spread can provide you an edge in parlaying side to total in exactly the same game. bj88 've already discussed, in a prior article, how to use these anomalous side and total combinations to hedge one another and increase your win with very little increase in risk. Such a bet, however, needed that you have an opinion on the side or the total. Parlaying is another method to increase your potential win on these games, or to develop a potential win in case you have no opinion.
You can find two games this Saturday that qualify. They are Virigina -25 over Duke with a complete of 48 �, and Kansas St. -24 � vs. North Texas with a total 46 �).
In the Virginia game, if you believe that Virginia covers the 25 points, they must hold Duke to only 11 points or the game will go over the total. The much more likely it becomes during the game that Virginia will cover 25 points, the more likely it becomes that the game will go over 48 �. The wider Virginia's winning margin, the much more likely the game will go over. If you like Virginia to cover the spread, and you also believe that Duke will never be shut out, in that case your possibility of winning a parlay on Virginia and the over are higher than the standard 25%. Likewise, if the scoring stays low, it really is not as likely that Virginia will cover the 25 points. Subsequently, the probability a parlay of the under with the underdog will win is greater than the normal 25%.
In case you have no opinion on the game, you can parlay the favourite with the "over" and the underdog with the "under" and collect sufficiently often to exceed the losses when both parlays lose. In the only real other game meeting the qualifications this week -- Friday's game between California -30 against New Mexico State with a complete of 58 -- the under has recently won with the underdog for an absolute two-parlay spread.
The closer the posted total is to the spread on the side, the better win-rate will be on the parlay "spread" bet. The co-dependency in side to total parlays is not as strong as parlaying first half and game totals (if it were, most books wouldn't normally allow such bets), but there exists a sufficient co-dependency in the games with low totals and high spreads to help make the strategy profitable long-term.
Not all bookmakers will allow you to parlay the side to the full total in exactly the same game, because increasingly more are realizing that these bets are occasionally co-dependent. But, enough books still do allow such bets for you to consider including such bets in your professional betting arsenal.
If your bookmaker provides "if/reverse" bets, it is possible to replace the parlay bet with an "if/reverse" bet and achieve greater success.