Line Yards and Highlight Yards: Splitting the Run Game's Credit

Yards per carry is the run game's box-score headline, and it answers almost none of the questions you actually care about. A back averaging 5.2 a tote could be running behind a line that opens a freeway every snap, or he could be a magician salvaging carries his blockers blew up. Yards per carry can't tell those apart, because it lumps two completely different jobs — the line creating space and the back exploiting it — into a single number, then lets one explosive run drag the average around. The fix isn't a fancier average. It's a set of stats built to split the credit, and once you've seen them you can never read a run game the same way again.

The one-sentence version: a run play is a collaboration, and line yards, opportunity rate, highlight yards, and stuff rate carve that collaboration into the part the offensive line earned and the part the back earned — which is exactly what yards per carry refuses to do.

Why yards per carry misleads

Two problems sink yards per carry as a measure of anything specific. The first is that it's an average, and rushing gains are wildly skewed: most carries gain a few yards, a handful break for big chunks, and those few explosive runs hijack the mean. A back with one 75-yard touchdown and nine stuffs for no gain "averages" 7.5 a carry and looks elite, when he was actually stopped on 90% of his work. The second problem is the one we're really here for: even when the average is honest, it credits the line and the back as if they were one player. A 4-yard gain where the line caved the front and the back fell forward is a totally different play from a 4-yard gain where the line got blown up and the back made two men miss to claw back to the line of scrimmage. Same number, opposite stories. To tell them apart you have to decide, yard by yard, who was responsible — and that's the whole idea behind line yards.

Line yards: the part the line earns

Line yards is a weighting scheme that assigns each rushing yard a share based on how much of it the blocking, rather than the back, plausibly produced. The widely used formula credits the offensive line with progressively less of each yard the farther downfield the run goes, because the deeper the back is, the more the gain is his own work in the open field rather than the hole the line made. The standard weighting goes like this:

• Runs stopped behind the line (a loss): the line gets credited with 120% of those yards — a tackle for loss is treated as more the line's fault than the back's, since the hole never opened.
• Yards 0 to 4 past the line: credited at 100% — this is the "the line made this hole" zone, all of it the blocking's doing.
• Yards 5 to 10: credited at 50% — shared territory, where the line got the back to the second level but the back is starting to earn it.
• Yards 11 and beyond: credited at 0% — once a back is more than ten yards downfield, that's on him, not the line.

Add up the line-credited portion of every carry, divide by the number of carries, and you get adjusted line yards per carry — an estimate of how much room the front five (and the scheme) created, with the back's open-field heroics stripped out. It's an approximation, not a measurement of who literally touched which yard, but it's a far better proxy for offensive-line run blocking than yards per carry, which gives the line full credit for a back's 60-yard sprint.

Opportunity rate and stuff rate: did the line do its job at all?

Line yards has a companion pair that asks a blunter, binary question on each carry: did the line give the back a chance, yes or no?

Opportunity rate is the share of carries on which the line gained at least four yards — i.e., the percentage of runs where the line "did its job" and handed the back at least the standard first-level hole. A high opportunity rate means the line is consistently creating space; it says nothing about what the back then did with it. Stuff rate is the dark mirror: the share of carries stopped at or behind the line of scrimmage for no gain or a loss. A high stuff rate against an offense means its line is getting beaten at the point of attack, the back is meeting unblocked defenders, or both. These two rates bracket the run game's floor: opportunity rate counts the good starts, stuff rate counts the disasters, and together they tell you how often the line even gave the play a chance before the back's ability entered the picture.

Highlight yards: the part the back earns

If line yards is the blocking's contribution, highlight yards is the back's. The idea is the complement: take only the carries where the line created an opportunity (gained that first-level hole), then measure how many yards the back tacked on beyond the opportunity threshold. Those extra yards — the broken tackles, the cutbacks, the open-field speed — are credited to the runner, because the line already did its part. Highlight yards per opportunity (the average bonus a back adds once he's handed a hole) is the cleanest single number for a back's individual ability, precisely because it conditions on the line having done its job first. A back with elite highlight yards is one who turns ordinary openings into chunk plays; a back with poor highlight yards is wasting the room his line gives him.

Put the framework together and a single run game decomposes into a clean chain of questions:

• How often did the line create a hole? → opportunity rate (and its inverse, stuff rate).
• How much room did the line create on average? → adjusted line yards per carry.
• How much did the back add once he had a hole? → highlight yards per opportunity.

Yards per carry is just the muddy sum of all three. The decomposition tells you which of them is driving the number.

A worked example: same yards per carry, opposite run games

Take two hypothetical offenses, each averaging exactly 5.0 yards per carry over 100 rushes. The figures below are invented to show the contrast, not measured from any real team:

Both average a tidy 5.0, so a box score grades them identically. But the Maulers are a line-driven offense — the front consistently opens holes (high opportunity rate, low stuff rate, strong line yards) and a merely-fine back falls forward through them. The Improvisers are the opposite: their line gets stuffed more than a quarter of the time and rarely opens much, but a special back rescues the average with huge highlight yards on the carries he does get loose. These two run games will age completely differently — replace the Maulers' back and they barely notice; replace the Improvisers' back and the whole thing collapses — and only the decomposition tells you that in advance. (Again, these figures are made up to illustrate the idea.)

How to read a run game beyond yards per carry

The practical move is to stop asking "how many yards per carry?" and start asking "where are the yards coming from?" When a rushing offense is humming, check whether it's the line (rising opportunity rate, falling stuff rate, healthy line yards) or the back (big highlight yards on a mediocre line). When it sputters, the same split tells you what broke: a line getting stuffed is a blocking or scheme problem; collapsing highlight yards on a line that's still opening holes is a back problem or a health problem. The decomposition also travels across personnel changes in a way yards per carry never can — line metrics tend to persist with the unit and the scheme, while highlight yards travel with the individual runner. That's why projecting a transfer back, or a line losing three starters, gets a lot more honest once you separate the two.

How to use it

• Distrust yards per carry on its own. It's a skewed average that fuses two different jobs — always ask whether the line or the back is driving it.
• Use opportunity rate and stuff rate for the line. They count how often the front did and didn't do its job, before the back's ability muddies the water.
• Use highlight yards for the back. By conditioning on a hole existing, it isolates the runner's open-field contribution from the blocking.
• Mind the explosive-run skew. One long touchdown can inflate yards per carry; the decomposition is far more stable because it scores each carry on its own merits.
• Project with the right piece. Line metrics tend to follow the unit and scheme; highlight yards follow the individual back — keep them straight when a roster changes.

The next time a back is "averaging six a carry," ask the question yards per carry hides: six yards earned by whom? A line that paves the road and a runner who builds his own are doing opposite work, and the only way to tell them apart is to stop averaging them together. Line yards and highlight yards do exactly that — they hand the credit back to the players who actually earned it.