Camp questions: Will the Lions defense remain dominant?

Stop me if this is breaking news, but the Detroit Lions no longer have Ndamukong Suh on their roster. Undoubtedly the centerpiece to the Lions defense, Suh's departure left a huge hole on the roster that they could never completely replace. The front office did their best by trading for Haloti Ngata in a savvy move just before free agency opened. But after losing the top free agent of 2015 and other important pieces, will the Lions be able to ride their defense to another playoff berth?

Who they lost

Ndamukong Suh

In losing Ndamukong Suh, the Lions not only lost one of the best players at the defensive tackle position, but they also lost a complete workhorse. Since 2010, only three interior defensive linemen have averaged more snaps per season than Suh. That's 875 snaps from 2014 that the Lions will have to find a replacement for in 2015. Ngata will eat up a lot of that, as he ranked fourth among defensive tackles in snap count between 2010 and 2013. However, at 31, Ngata's durability may start to come into question, especially considering he started training camp on the sideline due to a hamstring injury.

Nick Fairley

Then there's Nick Fairley. Fairley, though an enormous talent, has been overhyped as a "huge" loss for the Lions. Many national headlines presume that the Lions defense could survive with the loss of Suh, but Suh AND Fairley? No way.

There's some credence to that thinking. Fairley's 2014 season was off to a great start, earning a +11.1 Pro Football Focus rating through seven weeks, but an injury placed Fairley on the sideline for the rest of the season. How did the Lions defense respond without Fairley?

Not much differently. The Lions were actually better defending the run without Fairley and, although their pass defense suffered more, it wasn't because of a lack of pass rush. Sacks dropped only by 0.2 a game. Fairley's high level of play helped define the Lions defense early in 2014, but he wasn't integral to its season-long success.

C.J. Mosley

Perhaps just as important as Fairley's departure is the loss of the man who replaced him for the second half of the season, C.J. Mosley. Though Mosley didn't impress PFF like Fairley did (+5.4), he did provide an above-average amount of depth to the defensive tackle position.

With the loss of these three defensive tackles alone, the Lions find themselves looking to fill 1,713 snaps worth of defensive players. That's no easy task. That's an even harder task when the defensive line was considered one of your biggest strengths last year.

George Johnson

...and that doesn't even bring into account another loss along the defensive line, George Johnson. Johnson was lost during an odd series of events in which the Tampa Bay Buccaneers swiped him away from restricted free agency, then after the Lions contested the offer sheet, Johnson was traded away with a seventh-round pick for a fifth-rounder. Though Johnson saw a lot of action on the field (502 snaps), his meager grade of +1.4 on PFF accurately displays his mediocrity. Still, it's another body that the 2015 Lions defense needs to replace.

Who they gained

Haloti Ngata

As previously mentioned, the weight of Suh's departure will mostly fall on the shoulders of Ngata. Ngata has had no problem being the workhorse of the defense in the past, but the question remains: Will this be the year that age catches up with him? According to PFF, Ngata had his best season last year (at least since PFF's inception).

In terms of durability, Ngata has a near-perfect history. He has never missed more than two games in a season due to an injury. Though his snap count was slowly being reduced each year in Baltimore, he has still shown signs of being an anchor for the defensive line. He played in 546 snaps last season over 12 games (he missed four games due to a suspension). Average that out to a full 16 games and you get 728 snaps. While those aren't Suh numbers, they would still put Ngata around the 10-15 range of most snaps by a defensive tackle.

Tyrunn Walker

In addition to Ngata, the Lions added Tyrunn Walker, a rotational defensive tackle previously with the New Orleans Saints. Walker is a guy who was an under-the-radar signing, and an emerging force in the Saints defense. Last season, his impact with New Orleans was almost as big as Fairley's with Detroit:

In 2014: Nick Fairley: +11.1 @PFF rating on 297 snaps Tyrunn Walker: +8.0 rating on 306 snaps.

— Jeremy Reisman (@DetroitOnLion) August 5, 2015

Walker will almost certainly see an increased role with the Lions this season. Whether he will be able to keep up that kind of production on an increased amount of snaps remains to be seen.

A healthy Stephen Tulloch

Though this may seem like cheating in the category, a healthy Stephen Tulloch could be a huge addition to the Lions defense from 2014. Tulloch was coming off of his most successful season in 2013 when he unfortunately blew out his own knee during a celebration in Week 3. Tahir Whitehead did a valiant job replacing him, but his performance was nothing more than average (ranked 14th among inside linebackers). A healthy Tulloch means the Lions have a solid tackler and a decent coverage man back in the lineup. For a defense that struggled with athletic tight ends, that can go a long way in improving things in 2015.

Teryl Austin with a year of experience

Though Lions fans have blown Teryl Austin's significance to biblical proportions, the defensive coordinator's value cannot be understated. Even with star players like Suh and DeAndre Levy, the Lions' 2014 defense was defined by being greater than the sum of its parts. The defensive line, outside of Suh, was not full of very impressive individual performances. For much of the season, the secondary featured a sophomore cornerback, a 34-year-old, a fourth-string nickel corner and a safety who was benched late in the season. The center of the defense was manned by Whitehead, a guy who had never played a defensive snap in his NFL career.

Yet Austin was able to turn that ragtag team into a top five defense in the league. So while the Lions may be without the likes of Mosley, Johnson and Fairley, they now have Ngata, Walker and Tulloch. Austin has turned lesser cogs into a well-oiled machine before, and there's no real reason to think he can't do the same again this year.