Combo Props Explained (PRA, H+R+RBI)
Combo props put a single line on the sum of several stats, such as points plus rebounds plus assists (PRA) in basketball or hits plus runs plus RBIs in baseball. They are one market, not a parlay, and they price differently than the individual props combined because the component stats are correlated within a game.
What a combo prop is
A combo prop is a single over/under line on the sum of two or more stats for one player. Basketball's PRA (points + rebounds + assists) is the most familiar, alongside points + rebounds, points + assists, and rebounds + assists.
Baseball books post hits + runs + RBIs; football has passing + rushing yards and rush + receiving yards. It is one bet with one settlement: the components are added up and the total either clears the line or does not.
A combo is not a parlay
A parlay of points, rebounds, and assists needs all three legs to hit individually. A PRA prop needs only the sum, so a monster scoring night can cover a quiet rebounding one.
That flexibility makes the combo the easier bet to win at a given set of numbers, and books price it accordingly. The combo also settles at a single price rather than multiplying three separate prices together.
Why combos price differently than the sum of parts
Adding the individual lines rarely reproduces the combo line. Individual lines are set around each stat's median, and the median of a sum is not the sum of medians when the stats move together or apart.
The book prices the distribution of the sum directly. How spread out that distribution is depends on correlation between the components, which is exactly the information a naive sum of three lines throws away.
Correlation inside a combo
Most combo components are positively correlated through playing time: more minutes means more of everything, so big games tend to be big across the board and bad games bad across the board. In baseball, hits feed runs and RBIs directly, since a player who reaches base is the one positioned to score.
Some pairs partially offset. A guard who spends possessions shooting is not passing on those possessions, so points and assists can trade against each other within a fixed number of touches. The net correlation, positive or negative, is what shapes the fair combo line.
Researching combo props
The good news: hit rates work on combos exactly as on single stats. A player's L10 against a 34.5 PRA line is a directly measurable number, no correlation math required, because history already contains the correlation.
Check what drives the sum, though. A combo cleared mostly through one volatile component, like scoring spikes, is riskier than one built on three steady contributions, and minutes risk in blowouts threatens every component at once.
Frequently asked questions
Is a PRA prop the same as parlaying points, rebounds, and assists?
No. The parlay needs each stat to clear its own line; the PRA prop needs only the combined total to clear one line. A player can miss two individual lines and still smash the combo through the third stat.
Why is the combo line not just the sum of the individual lines?
Because the components are correlated. The book prices the distribution of the sum, and correlation changes how spread out that distribution is, so the fair line for the sum differs from the total of the individually posted lines.
Are combo props better or worse bets than single-stat props?
Neither inherently. Combos smooth single-stat noise, since one stat can cover for another, but their pricing bakes in correlation that is harder to evaluate by feel. Hit rates against the actual combo line, plus price comparison, are the honest way to judge them.