Two legs from the same game are rarely independent. Understanding the direction and strength of that correlation matters more than treating each leg as a separate coin flip.
Independent legs vs. correlated legs
A slip with legs from unrelated games behaves close to independent events multiplied together. A same-game slip does not: if a quarterback throws for a big passing-yardage total, his top receiver's receiving yards are more likely to clear a threshold too. That is positive correlation.
Positive correlation: stacking with the game script
Pairing a quarterback's passing-yardage or passing-touchdown leg with his primary receiver's receiving props is the clearest example of positive correlation — both legs tend to hit or miss together, because they are driven by the same underlying event (a pass-heavy, scoring game script).
Negative correlation: legs that compete for the same production
Two running backs on the same team competing for rushing attempts are typically negatively correlated — extra volume for one usually means less for the other. Stacking both "over" legs on a shared, limited resource is a different bet than it might first appear.
Why this matters for how a slip should be read
A slip's combined confidence is not simply the product of each leg's individual confidence once legs are correlated. Positive correlation among your legs means your true outcome distribution is more concentrated — you are more likely to hit all of them or miss most of them, and less likely to land in between — than independent math would suggest.
Using the slip builder with correlation in mind
SharpSlap's board lets you filter by game, team, position and market and assemble candidate legs in a slip builder, with each leg still carrying its own calibrated confidence and player history. Building a same-game slip intentionally — understanding which legs move together and which compete for the same production — is a more honest way to use that tool than treating every combination the same.
See the full NFL player props guide for how each market family is scored individually before it ever reaches a slip.