The MLB Underdog Edge: The One Pocket Fairline Tracks Forward
Fairline tracks one MLB pocket forward: moneyline underdogs the model rates at least 3 no-vig points above the market at lineup lock. Here is how a bet enters the pocket, how the two cohorts grade, and why the claim remains tracked hypothesis.
Updated Jul 2026 · Part of the models series
Fairline tracks one model pocket forward and publishes its record. This page describes what the pocket is, how a bet enters it, and what the record can and cannot tell you yet.
The pocket
The pocket covers MLB moneyline underdogs that clear two bars: a model win probability at least 3 points above the market’s own de-vigged probability, and a price of decimal 2.0 or longer.
Membership freezes at the first source-fresh quote after lineups lock. Price, edge, and stake freeze with it, so a later line move never rewrites a row that already entered. Every entry is a flat one unit. Nothing scales with the claimed edge.
How the record reads
The record runs two cohorts side by side. The hypothesis cohort holds every qualifying underdog, whether or not a book quoted a takeable price. The executable cohort holds only the flagged plays that had one, entered at that price. The first measures the selection rule. The second measures what a bettor could actually have done with it.
Both cohorts grade against the closing line as well as the final score, so the record reports closing line value alongside wins and losses. Closing line value covers why that benchmark reads faster than a plain win-loss record.
Where it stops
The pocket is a hypothesis under test, not a proven edge. Its status is tracked hypothesis, and it stays that way until a preregistered forward sample meets criteria fixed before the data came in.
The rule is MLB only. Running the same selection on NHL and EPL underdogs turned up nothing comparable.
Any single game still turns on ordinary variance, no matter how the record reads. Variance in betting covers how much of a single result is noise.