JACKSONVILLE – You know how you know the Jaguars' defense is good?

Many reasons, but among them is this:

It's getting tough through seven games to determine all the reasons it's performing at one of the highest levels in franchise history. Is it Calais Campbell? Or Jalen Ramsey? Or A.J. Bouye?

All are reasons, but there are reasons beyond those very obvious reasons.

The Jaguars' defense is by no means perfect yet. It too often has struggled to stop the run, and Jaguars Head Coach Doug Marrone on Monday said run defense absolutely will be a focus after the bye.

But this indeed is a very good defense – and it's built on more than one player. It is, in fact, built on far more than the aforementioned three players – all of whom have played at or very, very near a Pro Bowl level through seven games.

With the Jaguars at their bye week, we spoke with Campbell – who himself is playing at Pro Bowl/All Pro level with 10 sacks through seven games – and helped break down one player at each level of the defense who is having a major impact on a defense emerging as one of the NFL's best.

These three players aren't Jaguars' most-discussed defensive player at each level. But Campbell said their importance shouldn't be overlooked. Here they are:

1)Yannick Ngakoue, defensive end.Campbell's reaction to Ngakoue's 2.5-sack, seven-quarterback-hit performance against the Colts this past Sunday? "That's ridiculous." Equally ridiculous, according to Campbell, is Ngakoue's potential. A third-round selection from Maryland by the Jaguars in the 2016 NFL Draft, Ngakoue set a franchise rookie record last season with eight sacks. While he has been somewhat overshadowed this season by Campbell's early-season pace, Ngakoue has shown dramatic improvement this season and has 11 quarterback hits, three forced fumbles and three tackles for loss. He also is tied for eighth in the NFL with 6.5 sacks – a pace for 15, which would break the franchise record by three. The players around him in the NFL's sacks leaders read like the top of the Pro Bowl ballot – Joey Bosa, Von Miller, Julius Peppers, Melvin Ingram – and that's where Campbell said the second-year veteran belongs. "I told him [Monday] … he should consistently be in the Top 10 in sacks the rest of his career," Campbell said. "He's a very special guy. He's very explosive and has great bend. He's technique savvy. He has a lot of passion and love for the game. He doesn't lack anything except experience – and every day he's getting better."

2)Myles Jack, linebacker.It's perhaps a testament to the play of the secondary and the pass rush that Jack has yet gotten comparatively little recognition nationally. If Jack – who starts at strong-side linebacker and stays on the field in nickel situations – continues at his current level, that will come. A second-round selection in the 2016 NFL Draft from UCLA, Jack was a projected Top 5 selection before knee concerns. He is playing to his projected level this season with 56 tackles, including for four loss; he has had an impact when asked to blitz, registering two sacks and four quarterback hurries. Jack's speed in coverage also can't be overlooked as a reason quarterbacks are holding the ball and allowing the Jaguars to compile sacks at a rapid rate; Jack and linebacker Telvin Smith have combined to significantly limit yards after catch when quarterbacks check down. An overlooked element of Jack's season? His development in the huddle, where Campbell said he is improving each week calling the defense. "Myles has done a great job commanding the huddle, and controlling that energy level, making sure we're focused," Campbell said. "He's growing up fast."

3)Barry Church, safety.How good was the Jaguars' 2017 free-agency class? Good enough that Church – who signed as a free agent from Dallas in March – is the third player mentioned in the group. That's understandable considering the level of play of Campbell (Arizona) and Bouye (Houston), but it doesn't accurately reflect Church's impact. Church's impact plays this season have been memorable: the first sack of his career, a 51-yard interception return that broke open the victory over Pittsburgh, a big-time stop with Tashaun Gipson on Colts running back Frank Gore on third-and-1 that helped shape the first half. Campbell said Church's impact goes beyond highlights and extends to being a veteran leader in a secondary that is playing at a consistently high level. "He's brought veteran leadership, which I think is very, very important; he's a quarterback of the secondary," Campbell said. "He's making calls and checks. He fills the box, plays well against the run and he's great covering tight ends if he needs to. He plays centerfield back there if he has to. He can do it all, and that really makes a big difference because now we're versatile. You can put him anywhere, and he's a playmaker."