Juan Thornhill is a key building block on the Chiefs defense

Reviewing Juan Thornhill’s rookie season

Like most of the Chiefs defense, Thornhill encountered bumps in the road to start his rookie season. Adjusting to the speed of the NFL, and coming into a defense that was overhauled with eight new starters, it was to be expected. Every rookie is going to have his share of “rookie mistakes.”

Early in the season, Thornhill was hesitant at times to commit when playing in both single high and two deep zone coverages. He also had some struggles with quarterbacks who used their eyes to look off safeties to open up other routes.

Spagnuolo integrated the defense slowly, which had Chiefs fans about ready to stand outside of Arrowhead Stadium with their torches and pitchforks at one point. That all began to change starting in Week 7 when Kansas City traveled to take on their divisional opponents, the Denver Broncos.

What changed? Starting against the Broncos, Spags began calling heavy doses of blitz packages to get to the quarterback quickly. Joe Flacco, a statue in the pocket, never stood a chance. He also began to allow Mathieu to patrol more areas of the defense, leaving Thornhill as the deep middle defender. That confidence in his rookie paid off, as the Chiefs defense went on to have a complete turnaround from the start to the season.

Coming out of Virginia, Thornhill was known for his intelligence and versatility to play several roles on defense. Playing in the deeper zones with the receiver and quarterback in front of him is where he thrives. He spent time at both cornerback and safety in Virginia. Thornhill might not have great range, but it’s good enough when combined with his mental processing and navigation without false steps.

The ability to diagnose what the offense is wanting to do quickly, both pre and post-snap, can make up for athletic deficiencies. Here is an excellent example of that against the Oakland (now Las Vegas) Raiders last season on a 4th-and-1. Instead of trying to run it up the middle for that last yard, the Raiders take it outside, but Thornhill reads the ball, takes a great angle to the ball carrier, and makes the stop.

Thornhill’s anticipation allows him to jump routes underneath at a very high level. In the same game against the Raiders, he has a good idea of what the offense is wanting to do on this play. He communicates to cornerback Bashaud Breeland to let him know that he is taking anything inside. Watch how quickly Thornhill breaks downhill to jump the route and take the interception for six.

One of Thornhill’s best attributes is his spacing within zone coverage. Leveraging himself to be able to make a play on the ball or in that area of the field makes up for not having elite change of direction and acceleration.

Third and goal against the Los Angeles Chargers in Mexico. Keenan Allen motions pre-snap to allow for cushion off the line of scrimmage as he looks to break across the middle in the underneath zones. Thornhill reads it like a book. Allen’s path kept Thornhill from having a good chance to challenge the catch point, but his ability to adjust his angle to deliver a hit that knocks the ball out as Allen turns upfield got the job done.

Most of his work was from a deep safety role, but Spagnuolo did a good job of mixing him in closer to the line of scrimmage. Playing cornerback in college, Thornhill does a good job of sticking to the hip of most receivers. It’s the quick twitch receivers that gave him some trouble. Before the play was even snapped in this next clip, notice that the rookie safety already knows what’s coming.

Attacking the first receiver with physicality to push him back and take away the outside lane for the ball carrier, Thornhill forces him to work towards the rest of the defense. He does a great job keeping his chest clean, allowing him to shed the blocker and make the tackle.

Thornhill’s ability to play from single high and take away intermediate and deep areas of the field played a massive role in the defense gaining traction in 2019. With a highly intelligent, physical, safety in the middle of the field who also has great ball skills, Mathieu was able to take different roles within the defense. Cornerbacks were able to be more physical at the line of scrimmage, knowing they had Thornhill over the top. Quickly coming downhill against the run to make stops was another massive improvement from that position a year ago.

Once Thornhill became comfortable in the Kansas City defense, he displayed improvements in not allowing quarterbacks to look him off. He also developed more anticipation with an understanding of what offenses were trying to do.