Pundits have decided they've found that KC's pass protection is the villain behind Kansas City's 2025 passing regression. It's a satisfying story. It also isn't the one the data tells.

In 2024, the Chiefs took a sack on 6.38% of their dropbacks (41 sacks on 643 dropbacks). In 2025, that rose to 7.41% (47 on 634) — the 12th-worst rate in the league. That's real, and it's not nothing.

But it's also not enough to explain what happened to the offense. On a per-dropback basis, the Chiefs' passing game fell from +0.092 EPA/dropback in 2024 to +0.039 in 2025 — a collapse of roughly 60% in efficiency. A one-percentage-point bump in sack rate does not, by itself, do that.

The real culprit is a place nobody is looking: Patrick Mahomes' short throws.

Table of Contents

1. The short-throw collapse
2. Where the damage lives: 3rd down
3. The intermediate 3rd-down disaster
4. What didn't break: the deep ball
5. So what actually happened?

The short-throw collapse

On passes traveling 0–9 air yards, Mahomes went from one of the best in football to one of the worst in a single season.

CPOE — completion percentage over expected — measures accuracy relative to the difficulty of each throw. A +3.82 short-throw CPOE in 2024 was elite. A −1.28 in 2025 was, among 27 quarterbacks with at least 150 short attempts, the 26th-ranked mark in the NFL — better only than Joe Flacco (−2.63). For reference, the top of that leaderboard in 2025: Drake Maye (+10.62), Mac Jones (+8.21), Josh Allen (+7.34), Jalen Hurts (+7.18). Mahomes was closer to Flacco than he was to any of them.

To put a finer point on it: Mahomes threw 232 short passes in 2025 and completed 145. Had he simply held his 2024 completion rate on that same volume, he would have completed 164 of them. Nineteen additional completions on the easiest throws in the offense — that is a lot of drives.

Where the damage lives: 3rd down

If the short-throw regression were spread evenly across situations, it would still hurt. It isn't spread evenly. It's concentrated in exactly the down where accuracy matters most.

Mahomes' 3rd-down passing splits:

A +6.70 CPOE on 3rd down in 2024 wasn't just good, it was the kind of number that separates MVP-caliber play from everyone else. A year later it's below zero. Of Mahomes' 11 interceptions in 2024, only 1 came on 3rd down. Of his 11 in 2025, 6 came on 3rd down.

The team-level consequence:

• KC 3rd-down pass EPA/att: +0.196 in 2024 → −0.273 in 2025.
• KC 3rd-and-long (7+ yards to go) conversion rate: 34.1% (31 of 91) in 2024 → 16.0% (15 of 94) in 2025.

Cutting the 3rd-and-long conversion rate in half is a drive-killer. And drive-killers show up in exactly the way the Chiefs' 2025 offense showed up: efficient enough between the 20s, unable to sustain when it counted.

The intermediate 3rd-down disaster

Zoom in one more level, to the specific throws where Mahomes used to make his living: 3rd downs with the ball traveling 10–19 yards in the air. The "money" window for a QB who has to convert against soft coverage.

Four completions in seventeen tries. Three interceptions. From +0.918 EPA per attempt — genuinely elite — to −0.783. The attempt volume itself is telling: the Chiefs called this throw half as often in 2025, which suggests either the coverage stopped giving it up or the trust wasn't there. When they did go there, it was a catastrophe.

What didn't break: the deep ball

Here's the twist that ought to end the "his arm is going" narrative before it starts. Mahomes' deep-ball accuracy actually improved in 2025.

On throws of 20+ air yards:

More attempts, better completion rate, dramatically better CPOE, dramatically better EPA. If this were a "the offensive line is collapsing the pocket and Mahomes can't throw" story, the deep ball — which requires the most time to develop — would be the first thing to die. It's the one thing that got healthier.

Even the intermediate window overall (10–19 air yards, all downs) is only modestly down: 60.6% → 56.8%, CPOE +5.69 → +3.72. Real, but nothing like the short-throw or 3rd-down cliff.

So what actually happened?

The regression is very specific, and it doesn't match the shape of a protection problem:

• A protection problem would hurt the deep ball first. Mahomes' deep ball got better.
• A protection problem would show up as a sack-rate spike large enough to move the EPA needle by itself. KC's sack rate rose by ~1 percentage point — not nothing, but not sixty percent of the passing offense's efficiency.
• A protection problem doesn't preferentially destroy layups from 0–9 air yards on 3rd down. That's a rhythm-and-accuracy problem, and it lives in the quarterback and the route concepts, not the tackles.

What the data shows is that the NFL's most accurate short-throw quarterback in 2024 became one of its least accurate in 2025, that the damage concentrated on the down where his interceptions multiplied by six, and that the Chiefs stopped converting 3rd-and-long at a rate that would have looked bad in 2007, let alone in a Mahomes offense.

The offensive line got a little worse. Patrick Mahomes' short game fell off a cliff. Only one of those two things is big enough to explain what happened to Kansas City's passing offense in 2025.