Average runs tell you almost nothing about a single game. Building an MLB run model starts from that fact, because a team averaging four runs still scores zero, one or seven all the time. You will work a Poisson teaching baseline, compute the chance a team scores exactly four, and see why that number alone cannot price a moneyline. You have to sum across paired scores and decide how ties resolve, since a finished game is never tied. The lesson then turns to first five innings, where shrinking a nine-inning model by five-ninths breaks down. Batting order, starter usage and park all shift. If you price totals or sides yourself, this is how to avoid fooling yourself.
Learning objectives
Explain the mechanism, reproduce the worked examples, identify failure modes, and use the exercise to show comprehension.
