The best defensive linemen never get sacks
The box score has a column for sacks, and it does not have a column for anything else a defensive lineman does. The result is that for the last fifty years of NFL evaluation, defensive linemen have been ranked, paid, and remembered almost entirely by a stat that describes a tiny fraction of their job. Sacks are real and they matter, but the same way home runs are real and they matter: they are the part of the position's value that ended up in the scoreboard, not the part of the position's value that produced the scoreboard.
Most of what an interior defensive lineman does in a game does not register on any traditional stat sheet. It is also, frequently, the reason the defense played well. Front offices have known this for at least two decades, the advanced charting services have quantified it well enough to make contract decisions on, and the broadcasts have mostly not caught up.
What sacks actually are
A sack is the final outcome of a pass-rush rep that succeeded completely — the rusher beat the blocker, kept his angle, and got to the quarterback before the ball came out. The skill that produces sacks is real, but the variance around it is enormous. The same rusher with the same technique can win a rep against the same tackle on twenty plays, get to the quarterback on three of them, and get credit for one sack because the quarterback ate it on one and threw it away on the other two. The play-result column rolls a die that has very little to do with the underlying skill on each rep.
Sacks are also concentrated on the edges. Defensive ends and outside linebackers get the wide rushing lanes; defensive tackles almost never have a clean path to the quarterback because there are bodies in the way. A tackle who beats a guard and forces an interior pocket collapse usually doesn't get the sack — the edge rusher does, because the quarterback steps up to escape the tackle's pressure and runs into the edge's lap. The tackle's contribution shows up nowhere. The end's shows up in lights.
What pressure rate measures
The cleanest public metric for pass-rush effectiveness is pressure rate — the percentage of pass-rushing snaps on which a rusher either sacks the quarterback, hits him, or forces him to throw early or off-platform. This isn't a perfect measurement, but it's much cleaner than sacks because it captures the rep, not the result.
Pressure rate at the league's top end runs around 15% for edge rushers and around 10% for interior linemen. The numbers don't sound enormous, but they're the difference between a defense that wins and a defense that loses. A defense whose front four consistently produces pressure on fewer than 25% of dropbacks gives up a passer rating that ranks in the bottom third of the league almost automatically; a defense whose front four hits 35% is usually somewhere in the top five against the pass. The relationship is tight.
And the order of names produced by pressure rate is different from the order produced by sacks. The tackles who consistently crater interior pockets — Aaron Donald's whole career, much of Chris Jones's, the last few seasons of Cameron Heyward — show up at the top of pressure-rate leaderboards every year. Their sack totals are often in the high single digits while their pressure rates rival the league's best edge rushers. The defenses they played for rated near the top of the NFL throughout.
Run-stop win rate
The other half of an interior lineman's value is in run defense, and run defense has been even worse-served by traditional stats than pass rush. Tackles for loss are concentrated on a small number of plays. Most run defense is about not getting moved off a gap, redirecting the ballcarrier toward help, and forcing the run into a smaller area than it was designed for. None of that produces a stat-line entry.
The public charting services now publish run-stop win rate, which is, roughly, the percentage of run snaps a defender wins against his block within a small time window. The number isn't a verdict — it's a rep-by-rep metric, and not all reps are equal — but it correlates much more closely with how well a defense holds up against the run than the traditional tackle column does. A defensive tackle with a 35% run-stop win rate is destroying every run play he's near. A 25% is league-average. Below 20% means the player is being kicked around by guards.
The Aaron Donald case
Donald is the closest thing the modern NFL has had to an empirical proof that the box score doesn't measure interior defensive line play. By traditional stats, he had a great career. Across most of it, he was a top-ten sack producer for an interior defender. By pressure rate, run-stop win rate, and every team-level adjusted plus-minus metric, he was the most valuable defensive player of his era and not particularly close. The teams he was on graded out as elite defenses for as long as he was healthy and graded out as ordinary defenses immediately when he wasn't.
The cleanest evidence of his value isn't his own stat line. It's what happened to his teammates' stat lines. The edge rushers who played opposite him posted higher sack totals than they posted for any other team they played for, because the offensive line had to slide protection toward Donald and leave them in one-on- one looks. The cornerbacks behind him played with a faster quarterback clock than they played for any other team. The defense allowed fewer yards on the ground than every defensive coordinator in the league predicted before each season. None of these effects show up in Donald's row of the box score. All of them are him.
How to watch for it
The shortcut, on a single play, is to watch the interior of the line rather than the ball. You'll see one of three outcomes on every passing rep: the interior holds up cleanly and the quarterback steps comfortably into a throw; the interior gets pushed back into the quarterback's lap and forces him to scramble or short-arm the throw; or the interior gets blown up entirely and the play is over before it begins. Most of the difference between great defenses and bad ones happens on the second of those three. It almost never enters the box score.
Over a season, the right metrics — pressure rate for pass rush, run-stop win rate for run defense, and the various adjusted plus-minus methods that try to disentangle individual contributions from the whole front — produce a much more accurate ranking of interior defensive line value than sacks and tackles do. The best defensive linemen in the league are almost never the leaders in either traditional stat. They are, however, almost always the leaders in their teams' overall defensive efficiency, which is the part of the conversation that ultimately matters.
The lesson generalizes. Position groups whose value flows primarily through the things they enable, rather than the things they do directly, are systematically undervalued by box- score evaluation. Offensive linemen are the textbook example; interior defensive linemen are right next to them. The fix is not to invent more stats. It's to remember that the stats we have were optimized for the things that were easy to count, not the things that mattered most.