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Teryl Austin is back as coordinator of the defense, and that's very good news for Detroit.

(Mike Mulholland | MLive.com)

Ndamukong Suh might be the best defensive tackle in the game. He was definitely the cornerstone of the Detroit Lions' defense, and he made everyone around him better.

Then he went to Miami.

That's a major blow, and much of the offseason has been devoted to wondering how the Lions will manage without him.

But all that attention paid to Suh has overlooked the fact this defense still has a lot going for it -- enough, in fact, that Detroit could remain among the league's best on that side of the ball, even if it does take a step back up front.

Here are five reasons for optimism:

Return of 9 starters, plus Teryl Austin

While Suh was definitely the best player on that defense, it's worth pointing out Detroit was mostly average on that side of the ball during his first four seasons. It wasn't until Teryl Austin came aboard as coordinator that the entire unit took off.

Now, I'm not trying to argue that Austin was more important than Suh to Detroit's rise on defense. No scheme, and no coach, will work without good players. And Suh's the best at his position.

But clearly, Austin played a significant role in pulling all the pieces together. He was so good, and so well-respected, he nearly landed a head coaching job after just one season as a coordinator. That's crazy.

He struck out on the job front, though, and his return to Detroit should help mitigate whatever losses are felt by Suh's exit.

Austin's biggest strength is understanding what his guys do well, and don't do well, and gameplanning accordingly. Just look at what he was able to do last year, leading the league in defense for much of the season despite losing his starting middle linebacker and top three nickels in the first three weeks of the season. I'll repeat: That's crazy.

No matter what adversity hit, Detroit was able to adapt and roll on. That's Austin. He's back, and that's huge.

Austin won't have Suh anchoring things up front anymore, so his job is definitely harder. But he does have nine starters back from last year, including all the linebackers and defensive backs. So it's not like he's starting from scratch.

Stephen Tulloch back in the middle

The Lions didn't make many changes to the defense in free agency, with DT Tyrunn Walker the only notable signing. (And he might not even start, but more on that later). They do have a quasi-addition at linebacker, though, in Stephen Tulloch.

He's been a leader of the defense for a long time, and one of its better players, but was limited to just three games last year due to a torn ACL.

Detroit's defense continued to roll due to the surprisingly strong play of Tahir Whitehead. But Tulloch was playing some of the best ball of his career when he injured the knee, and remains the better option in the middle.

Now he's back, which is an upgrade in the middle. And Whitehead will take his year of starting experience and slide to the strong side, which should be an upgrade over Ashlee Palmer. (Though he still has to officially beat out Kyle Van Noy for the job.)

In other words: By getting back Tulloch, Detroit might be better off at two linebacker spots this season.

Darius Slay should take another step

Hall of Fame cornerback Rod Woodson predicted last offseason that Slay would turn a corner by Year 3. The Lions cornerback proved to be ahead of schedule.

Slay went to work after a turbulent rookie season in 2013, including spending some time with Woodson out in California, and bounced back in a significant way. He started all 17 games last season, allowed a QB rating of just 81.1 on balls thrown his way and was rated the 19th-best cornerback in the game according to ProFootballFocus.

His highest-rated game came against Chicago's talented 1-2 combo of Alshon Jeffery and Brandon Marshall at Ford Field. His most memorable performance was completely eliminating Dez Bryant in the playoff against Dallas.

Slay proved in those games he can play against anybody. Now it's just a matter of becoming more consistent. And with another season to settle into the scheme, to learn from Rashean Mathis, to rep against Calvin Johnson and Golden Tate, there's no reason to believe he won't be better in Year 3.

Caraun Reid trending up

Suh is gone, and that hurts. But his impact will live on in the form of Caraun Reid.

The defensive tackle barely played last year after Detroit selected him out of Princeton in the fifth round of the draft. But he latched onto Suh during the season. He studied Suh's game, his practice habits, his routine around the building. He journaled everything.

Then he accepted an invitation from Suh to work out with him this offseason.

Now Reid has returned to the Lions looking like an entirely different player. His physical development has been dramatic. He looks like a better, more technical lineman, too, though the real test will arrive when the pads go on in training camp.

But the Lions already see it, too, repping Reid ahead of Walker throughout minicamp.

It's impossible to say how good he'll be. But if the development is real, Detroit won't miss Nick Fairley and C.J. Mosley nearly as much.

Health at the nickel

People pay a lot of attention to who starts at linebacker, and that battle between Whitehead and Van Noy should be a good one. But with the proliferation of passing games around the NFL, Detroit actually has a nickel on the field more than a third linebacker.

That's become a critical position in today's NFL, and that's especially true for the Lions, who play in a division with Aaron Rodgers. But they lost their starting nickel (Bill Bentley) in Week 1 last season. Then their backup nickel (Nevin Lawson) in Week 2. And reserves like Cassius Vaughn and Don Carey went on to miss time too.

Detroit was scrambling just to find bodies to throw at the nickel. Guys were forced to play out of position. Free agents like Danny Gorrer -- remember him? -- were brought in off the street as stop-gaps.

Nickel was the greatest weakness on an otherwise very good defense for most of last season. And that shouldn't be the case this year, if for no other reason than Detroit has had an offseason to heal.

Veteran Josh Wilson is battling rookie Quandre Diggs for the starting job right now, and the once-promising Lawson will be added to the mix in training camp. They all have two working wheels. And that means Detroit is already ahead of where it was at the position most of last season.

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