StackLab

Why the number isn't a multiply

Legs out of one game aren't independent. An assist only exists because somebody scored, so when a line clicks, two or three players cash at once. Multiply those together as though they were separate games and the slip looks worse than it is.

We measured it on 1,131,690 real teammate pairs across three seasons. Two players both going over on points hits 13.9% more often than the multiply says, and assists 12.0%. Shots and blocks move together too, a little — 2.0% and 3.8%.

Goals are the exception, and it's the interesting one. Two teammates both scoring lands within a tenth of a percent of the plain product, because a team's goals come in a Poisson count split between the players who take the shots. One man scoring makes another man's goal no likelier. The multiply is right there, and the model says so rather than inventing an edge.

So StackLab doesn't multiply. Every game here is simulated thousands of times, and each posted line carries a record of which runs it hit. The chance a whole slip lands is the share of runs where every leg hit at once.

What the EV number means

EV is our win probability times what the slip pays, minus one. Positive means our model makes the parlay worth more than it costs. Negative means the book is ahead of us, and that's the common answer — it should be. Books hold a margin on every leg, and a parlay multiplies it.

Which is why the leg-count strip matters. Inside a fixed payout band, each extra leg multiplies the same hold again, so EV falls as the count rises. The strip shows that shape on the pool in front of you.

Every leg here is one a book is quoting

A leg only appears when a sportsbook is posting that exact line and we hold simulated runs behind it. The percentage beside a player is the same one his prop board shows — one model, one number, two pages.

Goalie saves come off the other team's shots, not off a number of their own. So a goalie's save total and the skaters shooting at him are the same shots counted twice, and the slip prices them that way.