The Colts arrived at Arrowhead Stadium on Sunday night looking to avenge their 31-13 loss to the Chiefs in the Divisional Round of last season's playoffs. While this game seemed ripe for another Kansas City rout, Indianapolis had other plans. Frank Reich's squad pulled off one of the biggest surprises of the 2019 season, stifling Patrick Mahomes and Co. on the way to a 19-13 victory.
It was the type of performance that should have defensive coordinators around the league studying the tape to see what strategies they can borrow from Indianapolis to slow down one of the most explosive offenses around. However, in this case, you could say the Colts had the right defensive game plan at the right time, and it might not be easily replicated.
Why was it the right time? Well, for one, Mahomes wasn't as effective after aggravating an ankle injury in the first half. He was forced to stay in the pocket more (72% of dropbacks before the injury; 86% of dropbacks after the injury), limiting his opportunities to create on the move. There's also no denying that the absence of receivers Tyreek Hill and Sammy Watkins, with the latter playing just two snaps Sunday night before exiting with a hamstring injury, helped the Colts frame their strategy and ultimately limit the Chiefs to just 13 points, which is half the previous single-game low for a Mahomes-led Chiefs offense (26 points vs. the Cardinals in Week 10, 2018).
That said, it was the way the Colts shut down Kansas City that really surprised us and further established a troubling pattern for the Chiefs. As we highlighted last week, all signs pointed to the meeting with the Colts being the perfect matchup for Mahomes to feast on what had previously been a zone-heavy defense, one that was coming into the game shorthanded due to injuries at linebacker and in the secondary. Entering Week 5, Mahomes had the lowest tight-window-throw percentage (11.7%) of all qualifying QBs since the start of the 2018 season, while the Colts forced tight-windows throws at the lowest percentage (8.1%) in that same time frame.
Furthermore, under defensive coordinator Matt Eberflus, the Colts had played zone coverage at the highest rate in the NFL (80.0%) since he was hired before the 2018 season, per Pro Football Focus. Mahomes had dominated against zone coverage in the first four weeks this season, completing 53 of his 70 attempts for a ridiculous 830 yards and 7 TDs. His out-of-this-world 11.9 yards per attempt and 147.9 passer rating vs. zone coverage led all qualifying QBs, compared to a much more mortal 8.3 yards per attempt and 95.6 passer rating vs. man coverage.
But as we all know, on any given Sunday, anything can happen, and this contest did not play out the way we had envisioned it. Eberflus completely reversed his coverage tendencies, dialing up a man-heavy coverage scheme for the first time as Colts DC on Sunday night. He employed man coverage on 73.3 percent of Mahomes' dropbacks, almost three times the rate of his previous high in a game during his Colts tenure (25.6% in Week 1 vs. the Chargers, 2019), according to PFF.
On the Chiefs' first two drives Sunday, which also happened to be their longest drives of the night, Eberflus used man coverage on 10 of Mahomes' 18 dropbacks (55.6%), per PFF. Mahomes was sacked once and only completed 5 of his 9 attempts for 34 yards vs. man coverage on those drives. But Mahomes destroyed the Colts' zone coverage on those two possessions, completing all seven of his passes for 110 yards and a TD. Seeing the early returns, Eberflus leaned even more into eschewing zone for man coverage, as he only employed zone coverage for three of Mahomes' 27 remaining dropbacks (11.1%).
Overall, Mahomes went 8 of 9 for 115 yards with a TD vs. zone coverage compared to 12 of 28 for 186 yards facing man coverage. All four of the Colts' sacks came when they were playing man coverage, and the Colts allowed less than half the yards per dropback in man (5.1) than they did in zone (11.9), according to PFF. The Colts' switch to a man-heavy scheme also forced Mahomes to throw into tight windows at a much higher rate than we expected heading into the game, with a 17.9% tight-window-throw percentage (fifth-highest in a game in his career), per Next Gen Stats.
"They played good defense. They played man coverage, they rushed with four people and they found ways to get pressure and to cover long enough," Mahomes said in his postgame remarks. "For us, Detroit did it last week, New England did it in the playoffs. I mean, we're going to have to beat man coverage at the end of the day. We've got the guys to do it, so now it's about just going out there and executing it whenever teams present it to us."
Now, if Watkins and Hill are healthy, leaning on man coverage would have been a far less enticing option for Eberflus. Hill practiced on a limited basis last week and seems to be getting close to returning from the shoulder injury he suffered in Week 1, and there's been no indication to this point that the Chiefs expect Watkins to miss significant time. Defenses set to face Kansas City won't be able to simply copy the Colts' strategy and expect the same results. However, it will be interesting to see if defensive coordinators at least try to stifle Mahomes and the Chiefs by playing tight man coverage regardless of their usual base defensive scheme. Most coaches would love to use man coverage on the majority of their plays, but the prevailing perception is that most secondaries don't have the talent to sustain that without giving up explosive plays.
Through five weeks, Mahomes is the only QB to face man coverage on over half of his dropbacks (53.8%), per PFF. While he has faced two of the most man-heavy teams in the NFL in the Lions (62.4%, second-highest rate in the NFL) and Ravens (41.9%, sixth-highest), the Colts game showed a zone-heavy play-caller that wasn't afraid to be flexible based on the Chiefs' weaknesses as the current roster stands. It goes to show the value that a field-stretcher like Hill brings to this offense.
In Mahomes' career, defenses have employed man coverage at a significantly higher rate (47.6%) when Hill isn't running a route compared to plays where he is running a route (29.7%). So, defenses play more man coverage against Mahomes without Hill as a threat, and they are more successful when doing so. Mahomes' efficiency vs. man drops across the board without Hill running a route, whether it's completion percentage (63.5% to 55.5%), yards per attempt (9.9 to 8.0), or passer rating (126.3 to 85.9). Mahomes has also been sacked at a higher rate vs. man coverage without Hill than he is with Hill (he's been sacked six times in each situation despite having 48 more dropbacks vs. man coverage with Hill running a route).
Next up for the Chiefs is a home game against the Texans, who have a Bill Belichick acolyte (Romeo Crennel) calling the shots on defense. Crennel plays man coverage at the seventh-highest rate this season (41.6%), joining the rest of Belichick's defensive coaching tree in the top seven (but that's a story for another time). Kansas City has not made any definitive announcement regarding Hill's status for the game, but getting him back would be a huge addition for this offense in what could be an epic shootout with Deshaun Watson and his talented receiving corps.
Whether Hill and Watkins are active or not, keep an eye on how the Chiefs fare against Houston's man defense. It will tell the story of whether a disturbing trend will continue to plague Kansas City or quickly die at the hands of the reigning NFL MVP.