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 when 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 are risking less with parlays, but they aren't. They believe they are able to win more with parlays, but they cannot. The bigger win with parlays is far outweighed by the bigger probability of losing. Parlay bettors are in fact risking more, with less probability of collecting.
A parlay is not an individual bet. It is two bets -- a one-unit bet using one team and a two-unit bet on another. Which team gets the two-unit bet? In point-spread betting at constant money odds, if both teams win or both teams lose no 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'll still make the bet?
A parlay is also 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 need to be there. The skilled handicapper is definitely wanting to make smart investments. He tries to remove the result of luck to the best extent possible in order to make his results as predictable as you possibly can.
Much like 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 taken for thousands because he didn't understand the co-dependency of certain bets. He allowed a player to consistently parlay the first half with the game. The player parlayed totals by combining the over in the first half with the over in the game, and the under in the initial half with under in the game. Both parlays were made in the same game. Each time the player won he would win 2.6 times his bet. Betting $100 on each parlay, if one of these won, the ball player would win $260 and lose $100 on the other 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 for the book. The normal coin-flip probability of winning one parlay out of the two are 50-50. As far as the bookie was concerned the bettor should be winning $160 half enough time, and losing $200 half enough time. The bettor, however, making $500 parlays, was ahead a lot more than $20,000 after 6 months, and the book began to look at what the bettor was doing more carefully.
The issue for the bookmaker was that the two halves of each parlay were co-dependent. At the end of the initial half, the bettor was almost never in a 50-50 situation.
Take the Thursday night game between Utah and Air Force. The game total was 53 and the first half total was 27. By Hi88 of the first half, the score was 31-21, for a total of 52 first-half points. The initial half of among the 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 game. Obviously the chances of winning the "over" in the overall game weren't 50-50 but better than 99% and only the "over." The player only had a need to win the first 1 / 2 of the parlay to be virtually assured he would collect 2.6 times his money instead of just $10 for $11.
Before you rush out to try this, be aware that most off-shore books are far too smart to permit you to parlay first half to game. If they do permit you to do this, start worrying about collecting because that book will be taken up to the cleaners.
There are, 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 medial side and total in the same game.
Any game where the total is significantly less than double the spread can provide you an edge in parlaying side to total in exactly the same game. We've already discussed, in a prior article, how to use these anomalous side and total combinations to hedge each other and increase your win with hardly any increase in risk. Such a bet, however, required that you have an impression privately or the total. Parlaying is another method to increase your potential win on these games, or even to create a potential win in case you have no opinion.
You can find two games this Saturday that qualify. They're Virigina -25 over Duke with a total of 48 �, and Kansas St. -24 � vs. North Texas with a complete 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 full total. The much more likely it becomes during the game that Virginia will cover 25 points, the much more likely it becomes that the overall game will review 48 �. The wider Virginia's winning margin, the more likely the game will go over. If you want Virginia to cover the spread, and you believe that Duke will never be shut out, in that case your possibility of winning a parlay on Virginia and the over are greater than the normal 25%. Likewise, if the scoring stays low, it is less likely that Virginia covers the 25 points. Consequently, the probability a parlay of the under with the underdog will win is higher than the normal 25%.
When 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 total of 58 -- the under has already won with the underdog for an absolute two-parlay spread.
The closer the posted total is to the spread privately, 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 would not allow such bets), but you will find 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 help you to parlay the side to the total in the same game, because increasingly more are realizing these bets are sometimes co-dependent. But, enough books still do allow such bets so that you can consider including such bets in your professional betting arsenal.
If your bookmaker provides "if/reverse" bets, you can replace the parlay bet having an "if/reverse" bet and achieve greater success.