The easiest way to understand middling a game is with an example: The New England Patriots open as 7 point favorite against the New York Jets. A bettor likes the Patriots and places a wager on the Patriots -7. During the week the line moves and the Patriots become a 10 point favorite against Jets.
What is the most successful betting strategy? Hedging bets is by far the most successful betting strategy. This is where you're able to place multiple bets to cover all possible results and still make a profit regardless of the outcome of the game.