The runline is a handicap type market and it is one of the most popular baseball betting markets. The underdogs receive a ‘start’ of a number of runs and the favourites start minus a number of runs. If you back the underdogs +1.5 runs you need them to lose by 1 run or less (or win) for you to win your bet. Those who go for the favourites -1.5 runs would need their team to win by 2 runs or more.