Same-game parlays (SGPs) feel intuitive—tie a narrative together and juice the payout. The trap is hidden correlation. When legs move together, the true combined probability is higher than the book’s naive pricing, or the book clamps it with limits and inflated hold.
What correlation really does
Correlation means one leg raises or lowers the chance of another. A QB over often boosts a WR over; a defensive slugfest props undercuts multiple player overs. If you ignore this, you either overpay for redundant edges or get blocked by pricing rules.
Books defend with guardrails. Some SGP engines ban “too obvious” combos; others bake in extra vig the moment legs align. Your job is to tell real synergy from priced-in redundancy before you click “add.”
Core terms in plain English
Positive correlation: one leg hitting makes the other more likely.
Negative correlation: one leg hitting makes the other less likely.
Redundancy: two legs that are basically the same bet in different words.
Common correlation traps
Yards and TDs for the same player look different but ride the same usage spike. Pairing both can be pure redundancy unless the book underprices the combo. Team spread with QB over is similar; the path to covering often runs through volume.
Game script is the biggest hidden leg. Unders plus multiple player overs fight the same clock. Conversely, alt unders with RB carries over can align in slow, run-heavy scripts; mixing unders across passing props in the same script is usually a leak.
Quick correlation table
| Leg Pair | Correlation | Pitfall You Miss |
|---|---|---|
| QB Over + WR1 Over | Positive | Redundant usage; extra juice applied |
| Team – Spread + QB Over | Positive | Cover path = passing volume |
| Game Under + Multi Receiver Overs | Negative/Clash | Clock kills volume across the board |
| RB Carries Over + Alt Under | Positive | Script aligned; often pre-priced |
| Sack Over + QB Yards Over | Negative/Clash | Pressure suppresses clean yards |
Pricing tells and book defenses
If an SGP price looks worse than multiplying singles, the engine added a “correlation tax.” When it looks better, check for a missing dependency (e.g., WR2 over tied to slot usage, not QB volume). Either way, confirm with a quick implied-probability check.
Limits are a tell too. Books slash max stakes or disallow certain leg pairs when internal models flag tight linkage. If you can build any combo at full stake, assume a fat house margin on that template.
Practical tests before you bet
Swap one leg for a nearby alt line. If the parlay price barely changes, the engine is clamping correlation—value is thin. Split the parlay into two smaller narratives; if each prices fairly alone but not together, the dependency is already taxed.
Smarter SGP construction
Aim for complementary, not duplicate, signals. A QB over plus a receiving over from a secondary option can work if the secondary role spikes on specific coverages. Correlate across different stat families—pace or plays run with one player prop—rather than stacking three versions of the same story.
Use negative correlation intentionally to balance tails. For example, pair a modest QB over with an opponent receiver over in likely shootouts; both win in high-play states without being the same ticket. You’re hunting clean, lightly priced relationships, not layered mirrors.
A simple workflow
- Write the game script first in one sentence (e.g., “fast pace, trailing dog throws 40+”).
- Pick one primary leg that directly expresses that script.
- Add exactly one supporting leg from a different stat family.
- Price the parlay vs. singles; abandon if the “tax” exceeds your edge.
Bankroll rules and review
SGPs spike variance. Keep stakes to 0.25–0.5 units unless you have measured edge. Track CLV on each leg’s closing number; if you never beat close on singles, your SGP edge is likely imaginary.
Log outcomes by script, not just by leg. Did the game play your way yet the parlay still failed due to redundancy? Adjust templates, not bet size. Two weeks of disciplined notes will expose which correlations the book overprices—and which it already owns.
Quick discipline list
- Avoid mirrors: don’t triple-stack one usage story.
- Use alt lines sparingly; they attract bigger correlation taxes.
- Test price elasticity by swapping legs/lines.
- Cap SGP stake and judge success by process (CLV, script fit), not single tickets.