This page briefly defines and links to the explanation of each key term in the ORN series (including itself). I’ve sorted these entries loosely into a logical order, so if you’re looking for a specific term, use your browser’s search function since this list is not ordered alphabetically. Here’s a link to the hub for the entire series.

**ORNs**: “Observational Rushing Numbers” (which previously went by a different name) are the collection of stats I either track or derive from that tracking when charting any running back’s game. As the “O” suggests, there is an observational, subjective nature to these metrics, which (when used by someone with somewhat of a trained scouting eye) allows them to translate intangible skill evaluation to quantitative data. In English, it’s a one-size-fits all system that, with the help of some math afterward, allows us to compare the end product of different backs’ skill sets.**Running Back Generated Yards**(RB-GY, GY): On a given run, how many yards the running back generated on his own. I record this number by asking, “how much would a back with replacement-levels of every skill gain on this run?” The difference between those hypothetical yards and the actual yards gained is RB-GY.**Identification Rate**(ID Rate): On runs where the blocking unit opens a hole for the back, if the back sees the hole and makes his way there (regardless of whether he makes it there and through it), he’s identified it. The ID Rate over a set of rushes is the amount of holes the back identified divided by the total number of holes opened by blocking. It effectively measures the combination of a back’s vision and patience.**Hit Rate**: When a back has identified a hole, they’ve “hit” the hole if they make it to/through it. Hit Rate is the amount of holes hit divided by holes identified over a set of rushes. It effectively measures the combination of a back’s quickness, agility, decisiveness, functional strength, and balance.**Success Rate**(SR): SR takes the amount of holes hit and divides it by the total amount of holes created in a set of rushes. It combines Hit Rate and ID Rate and measures how good a back is at getting through holes when the blocking has opened a lane for them.**Offensive Line Generated Yards**(OL-GY): OL-GY is the amount of yards that the blocking unit has effectively created for the back. It is the amount of yards that the uniformly replacement-level back would gain in the question I ask in the RB-GY phase. Once a single player would tackle the replacement-level back on a run, OL-GY shifts to RB-GY, so OL-GY can be seen as a sort of weakest-link measure, since one weak link would theoretically diminish an offensive line’s numbers on his own. It can also be seen as the amount of push an offensive line gets, especially on runs without a hole created.**Generated Yards per hole hit**(GY/Hit): The total amount of GY divided by the number of holes a back hits in a set of rushes. This was the primary tool used to reflect a back’s creativity before I had play-by-play data to use (and thus couldn’t separate GY by stuffs and hits). Because HGY/C and SGY/C are much better tools for measuring creativity–they have the nuance to measure two very different skill sets (there is no correlation between the two stats) and are not biased by OL play, unlike GY/Hit–they have taken over GY/Hit’s spot in the Supercomposite, sharing equal weight.**Hole Rate**(HR): HR takes the total amount of holes an offensive line creates divided by the total amount of plays in a set of rushes. The statistic measures an offensive line’s ability to provide backs with opportunities to run in daylight, and works as more of a measure of the whole unit as opposed to OL-GY.**Power Broken Tackles**(Powers): How many times a back broke or avoided a tackle by primarily using their power.**Elusive Broken Tackles**(Eludes): How many times a back broke or avoided a tackle by primarily using their elusiveness.**Broken Tackles**(BTK): Total amount of times a back broke or avoided a tackle. It is calculated as the sum of Powers and Eludes.**Broken Tackles per hit**(BTK/Hit): BTK/Hit takes the total amount of times a back broke or avoided a tackle and divides it by the number of holes a back has hit. It effectively measures how good a back is at dodging tackles, and is used on a per-hit basis instead of a per-carry basis because it’s much harder for backs to break tackles without daylight.**Supercomposite**: The Supercomposite uses standardized, weighted ORNs to (pretty accurately) reconstruct a back’s Yards per Carry mark. The member stats are meant to be correlated as little as possible, similar to Dean Oliver’s Four Factors. With the exception of OL-GY and HR (with an r-squared value that hovers around 35%), the member stats indeed have very little dependence. The Supercomposite acts as a way to say how much one skill set pitches into rushing efficiency (and thus, ability) as a whole. The current Supercomposite weights are:- OL GY: 25%
- HR: 25%
- HGY/C: 20%
- SGY/C: 20%
- SR: 10%

**Running Back Composite**(RB Composite): The RB Composite takes the running back elements (HGY/C, SGY/C, and SR) of the Supercomposite and uses the same proportional weights in order to grade a back’s effective rushing ability with a single number.**Offensive Line Composite**(OL Composite): The OL Composite takes the blocking elements (OL-GY, HR) of the Supercomposite and uses the same proportional weights in order to grade a blocking unit’s effective ability to contribute to the running game with a single number.**Stuff**: Any run in which the blocking unit does*not*open a hole for the running back.**Hit Generated Yards**(HGY): Total RB GY on every play in which the back hits a hole.**Stuff Generated Yards**(SGY): Total RB GY on every stuff (when the blocking doesn’t open a hole).**Hit Generated Yards per hole hit**(HGY/C): HGY/C takes HGY and divides it by the total amount of holes that a back hits in a set of rushes. HGY/C is one half of the new creativity equation. It measures how well a back generates yards when they see daylight and an opportunity to work in the second level. That effectively evaluates a back’s downfield vision, acceleration, speed, elusiveness, and balance.**Stuff Generated Yards per stuff**(SGY/C): SGY/C takes SGY and divides it by the total amount of stuffs in a set of rushes. SGY/C is one half of the new creativity equation. It measures how well a back generates yards in tight confines when there’s little room for the back to work. That effectively evaluates a back’s decisiveness, strength, balance, and agility (some backs can sidestep backfield tacklers much better than others).**Generated Yard Rate**(GY Rate): GY Rate is the proportion of runs in a set of rushes in which the back generates some range of yards. For example, 10-plus Hit GY Rate (H 10+ Rate) takes the amount of runs in which a back hits a hole and generates at least 10 yards and divides it by the total amount of holes the back hit. GY Rates, by default, will filter out any runs with box disadvantages outside a range between 0 and 1. Abbreviating a GY Rate goes as follows:- H/S (depending on if we’re looking at hits or stuffs) + (GY range) + Rate
- Four-to-nine Hit GY Rate = H 4-9 Rate
- Over three Stuff GY Rate = S >3 Rate

**Gash Rate and Chunk Rate**: I’ve named the two most important GY Rates, H 10+ Rate and S 3+ Rate, “Gash Rate” and “Chunk Rate”, respectively.**Box disadvantage**(Box +/-): How many more defenders there are than blockers in the box when the ball is snapped. Because the quarterback and running back won’t block on the run, Box +/- is equal to defensive box players minus offensive box player plus two. Box +/- currently serves mostly as a filtering tool to reduce sets of plays to ordinary circumstances.**Percentile performance**: Percentile performances use one of the Composite ratings to translate either a back’s or blocking unit’s performance in a single game into a relative ranking among all others. Analyzing percentile performances allows us to look at overall game-to-game variance, ceilings, floors, and trends in an RB’s or OL’s play.