This is a very common occurrence in sports betting and sportsbooks have the full right to shift the spread or odds for any given match prior to it starting. Many factors can influence a change of the spread such as injuries, the number of bets coming in for either team or the weather, to name a few. Depending on the timing of placing the bet, the bettor can also have an advantage or a disadvantage depending on which way the spread has shifted.
For example: New England –2.5 (–110) or Philadelphia +2.5 (–110) means you’d wager $110 for the chance to win an additional $100 if you bet on the point spread. Depending on which side is receiving the most action, a sportsbook will often move the line up or down in order to incentivize betting on the less popular side. Injuries or unforeseen changes can also impact a point spread gambling line. Point spreads are often listed with a half-point (ex: 2.5) in order to prevent the final margin from landing exactly on the point spread (ex: 10-point spread, final score of 20–10). A “push” or “tie” usually goes to the house or sportsbook, unless another arrangement has been agreed upon beforehand.
A “Win/Place” or “Each Way” bet (aka EW) refers to a bet where the chosen selection must either win or place within the payout terms. The bet is divided in two parts,the “Win” part and the “Place” part of an equal stake or wager. Settlement of such bets will take into account the applicable rules governing the "Win" and "Place" bets, namely the Sport-specific rules as well as any applicable ‘Dead Heat Reductions’.
Notice that point spreads adjust the score for the favorite team. This is easiest to see with an example: If the New York Knicks are playing the Boston Celtics, and Boston is favored to win by a 4-point spread, then a bet on Boston only pays out if Boston wins by more than 4 points. A bet on New York pays out if New York wins or if they lose by less than 4 points.
That was all before Charles McNeil, a math teacher from Chicago, invented the concept of the point spread. An avid gambler, McNeil created what he called “wholesaling odds” and started his own bookmaking operation in the 1940s. He started out offering this new style of betting on football, but his business model grew to include basketball. McNeil changed the way sports betting was done, and his legacy lives on today in what we now call the point spread.