by Charles McDonald

One of the pleasant surprises of the 2017 season has been the play of the Jacksonville Jaguars defense. With Calais Campbell, A.J. Bouye, and Barry Church joining a unit that already featured Jalen Ramsey, Yannick Ngakoue, and Malik Jackson, most people expected them to be one of the league's better units, but they have absolutely exploded as a group and exceeded all expectations. Jacksonville currently boasts the league's No. 2 defense according to DVOA and has the league's top pass defense by a considerable margin.

In recent weeks, Jacksonville has picked up steam as a dark horse candidate to knock off the New England Patriots or Pittsburgh Steelers on the road come January. Jacksonville has elite cornerback play backed by a frenzied pass rush that currently leads the league in sack rate and overall sacks. The Jaguars are allowing just 3.7 adjusted net yards per attempt, compared to the league average of 5.9 adjusted net yards per attempt.

The Jaguars' run defense still leaves room for improvement, but in a league centered around the ability to be explosive and efficient through the air, Jacksonville's dominant pass defense makes them a legitimate Super Bowl contender. However, after getting shredded by Kyle Shanahan, Jimmy Garoppolo, and the red-hot San Francisco 49ers (eighth in offensive DVOA since Garoppolo became the starting quarterback in Week 13), there's a definite question to be asked about Jacksonville's chances against supreme coaching talents in the postseason.

On the surface, there's no reason for Jacksonville's juggernaut defense to give up 37 points to an offense featuring middling skill talent like George Kittle, Trent Taylor, and Marquise Goodwin. Shanahan, however, took Jacksonville defensive coordinator Todd Wash to the woodshed throughout the entire game. Shanahan stretched the field vertically and horizontally with his play-action passing attack, and Wash never had an answer for him.

Do the Jaguars have the coaching staff to maintain a postseason run? A closer look at the 49ers' obliteration of the Jaguars' defense shows some cause for concern.

One of the staples of Kyle Shanahan's playcalling is the play-action bootleg. On this particular play, the 49ers paired the bootleg by Garoppolo with their typical split-zone look, sending fullback Kyle Juszczyk into the flat on a passing route. Jacksonville played their typical three-deep coverage look, but safety Tashaun Gipson was completely unprepared to run with Juszczyk on the flat route.

What makes this even more difficult to defend is the fact that Shanahan called this play on first-and-10. Play-action bootlegs like this are very effective because they're tendency-breakers for the offense. Most defenses expect a run on first down; Jacksonville certainly did, filling their initial run fits as the passing routes developed. This set up a 49ers touchdown one play later.

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Another way the 49ers played chess to the Jaguars' checkers was how they isolated routes against Paul Posluszny, who isn't exactly the fastest linebacker in the league. San Francisco called up play-action off a split-zone look again, but this time out of 21 personnel (two backs, one tight end) instead of 12 personnel (one back, two tight ends, counting Juszczyk) like they had on the previous play.

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Jacksonville is playing Cover-1, which leaves Posluszny in man coverage against Juszczyk (who lines up in the backfield this time). Since the 49ers fake the run to start the play, Posluszny has to play his run fit at the snap of the ball. Once he realizes the 49ers are running a pass play, it's too late -- Juszczyk has already started his wheel route down the field. Posluszny has no chance to catch the speedy fullback, and Jacksonville ends up giving up an explosive play through the air.

Isolating explosive playmakers on less athletic defenders is a sign of good game-planning and coaching. The 49ers also attacked Posluszny on passing concepts that simultaneously stretched the field vertically and horizontally for interior defenders.

Shanahan dialed up a Y-Cross concept against Jacksonville's Cover-3 look to stress Posluszny in the middle of the field. As the routes unfold, George Kittle's crossing pattern forces Telvin Smith to match him in coverage across the field. That puts Posluszny in a bind, as he gets lost in the middle of the field between the deep dig by Louis Murphy breaking behind him, and the running back's quick out route breaking in front of him.

Posluszny takes one false step towards the running back, giving Garoppolo the window he needs to hit Murphy for a first down. Once again, the 49ers got the Jaguars' weak link in a position of conflict in the middle of the field.

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At various points in the game, the Jaguars did give themselves a chance to compete with the sheer level of talent they have on defense. They were able to force Garoppolo into his only interception of the day by revving up their pass rush for a quarterback hit. Jacksonville will always have a chance to win because of their dominating pass rush; it's arguably the one thing they do best as a defense. Campbell and Ngakoue have brought the heat all season long.

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It's a good thing the Jaguars did get home to disrupt Garoppolo, because the 49ers did have options for a touchdown on the play. Marquise Goodwin is uncovered breaking towards the middle of the end zone, and Kendrick Bourne, the intended target on the play, was about to be open as he broke towards the back pylon on his corner route.

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That's a situation where Jacksonville's talent can overcome poor planning by the coaching staff. However, the 49ers were able to whirl around the Jaguars for one more big play to ice the game at the end of the fourth quarter. Shanahan called a fake jet sweep into a toss against the Jaguars' man coverage for a 30-yard touchdown run by Matt Breida.

The motion pulls Ramsey away from potential run support on the edge, leaving Jacksonville with no force defender as the 49ers' blockers reach the second level of the defense.

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This is the interesting situation that the Jaguars find themselves in. They clearly possess the talent to be a Super Bowl-winning defense, but their simple schemes are easily exploitable by coaches who have a bit of creativity in their arsenal. Shanahan absolutely fits that mold. Bill Belichick, Josh McDaniels, Mike Tomlin, and Todd Haley are all coaches who have had postseason success, and they're going to be the coaches in Jacksonville's way during the postseason.

I personally still believe that Jacksonville has the best chance to beat the Patriots in the postseason due to their physical brand of pass defense and ability to rush the passer. However, a sliver of doubt had to creep into the minds of Jaguars supporters as they saw their defense get ripped to shreds by a handful of players who might be training camp cuts in 2018.

The postseason is a different animal than the regular season; Doug Marrone, Todd Wash, and the rest of the Jaguars staff need to figure out a way to protect themselves a bit better against the more creative coaches in the league, or else Jacksonville's return to the postseason will be short.