Game seven and what it does to a total
Deciders are lower scoring than the games before them, and the reason is rotations and fouls rather than tension. How to price the difference.
The story about deciders is that tension makes shooting worse. The observable effect is real and the mechanism is duller than that: fewer possessions, more stoppages, and eight players instead of eleven.
Where the possessions go
A coach with no next game shortens the rotation to the players they trust. Those players play more minutes than they have all series, and tired players walk the ball up. Pace falls, and since a total is possessions multiplied by efficiency, the possessions half does most of the work before efficiency is discussed at all.
The second effect is the endgame. A close fourth quarter produces intentional fouls, timeouts and reviews, all of which burn clock without producing possessions for either side. A game that is close late has structurally fewer possessions than a blowout of the same length.
Which means the total interacts with the spread
This is the part that gets missed. The pace reduction is largest when the game is close, so the under is correlated with the game being tight. A bettor holding the under and a large spread is holding two positions that fight each other, and neither price knows the other exists.
What to look for in this specific game
Whether either coach has actually shortened the rotation in games five and six, which is observable, and whether the two sides play at similar pace. Two fast teams produce a decider that is slower than their average but still fast; a fast team against a slow one produces a game the slow team controls.
One more thing the market handles well
Home advantage in a decider is larger than in a regular season game and smaller than the crowd noise suggests. Most of the measurable effect is officiating rather than shooting, and officiating effects are among the best studied numbers in the sport, which means they are thoroughly priced.
What this does not tell you
The effect is modest and it is already largely in the price. Anybody claiming a large systematic edge on playoff unders is describing a market that stopped existing about fifteen years ago.
Common questions
Are game sevens lower scoring than other playoff games?
Modestly, yes, and the effect is consistent enough to be pricable. Shorter rotations and more deliberate late-game play both reduce possessions.
Why does pace drop in a decider?
Coaches shorten rotations to their best players, who are tired, and late-game situations produce more stoppages and free throws, which consume clock without producing possessions.
Is the effect already in the price?
Usually most of it. The totals market has priced playoff basketball for a long time, and the question is whether this particular matchup is more or less affected than the average.