MLB Prop Research

What you're comparing

Two independent opinions about the same event. The sportsbook line implies a probability — a +480 home run prop implies about 17%. The model produces its own probability for the same batter from matchup, park, and form inputs. This page's parent tool puts the two side by side for every batter with a posted line and shows the gap in percentage points.

Read the gaps honestly

HR props are quoted Over-only, so a book's implied probability includes its margin — roughly a point of vig that can't be stripped out the way two-sided markets allow. That means small gaps are noise, not signal. A disagreement is a reason to look closer at the matchup, never a recommendation by itself.

To see the full research flow applied to one real prop — lineup, projection, matchup context, book comparison, and how a past call graded — read the worked example.

Tracked forward, not backfilled

Model-vs-book comparisons accrue from the day a line is captured — never reconstructed after results are known. How the top of the board has actually performed is public on the accuracy page, and the model's inputs are documented in the methodology.