What the MLB Run Line Actually Means
The run line sets the favorite at -1.5 runs and the underdog at +1.5 runs. A bet on the favorite only pays out if that team wins by two or more runs. Back the underdog on the run line, and your ticket cashes even if they lose by one. Because baseball scores stay low, a -1.5 line is genuinely hard to cover
— that difficulty is priced into the odds, which is why a run-line favorite often carries a shorter negative price than the same team on the moneyline. Pitching matchups, bullpen depth, and ballpark factors all shift where the line opens and how it moves before first pitch. Checking line movement from open to close tells you where sharp money landed.