PHOENIX -- The Detroit Lions will try to do something no other NFC team was able to accomplish in 2014.

Start four players on defense who are at least 30 years old, and still make the playoffs.

Detroit brought back cornerback Rashean Mathis, safety James Ihedigbo and middle linebacker Stephen Tulloch from last year's second-ranked defense, plus added tackle Haloti Ngata to the mix.

Mathis, Ihedigbo and Ngata were all outstanding last year, while Tulloch was outstanding in his last full healthy season in 2013. But they'll also be 35, 31, 31 and 30, respectively, when next season kicks off.

And that makes the Lions an old defense by today's standards.

"Yeah, I'm concerned about it," general manager Martin Mayhew said last week.

But not as concerned as he is about bringing in good players. And make no mistake -- the Lions defense might be getting up there in years, but these guys can ball too.

Mathis was the 12th-best corner in the game last year, according to ProFootballFocus. Ihedigbo helped form one of the best safety tandems in the league with Glover Quin (who, at 29, is no spring chicken himself). Tulloch was one of the steadiest players on the team until tearing his ACL in Week 3 last year.

And Ngata, the new guy, is a five-time All-Pro who was probably Detroit's best recourse at defensive tackle once Ndamukong Suh decided to sign with Miami.

"I'm more concerned with production and effectiveness than I am (concerned about age)," coach Jim Caldwell said, "because I think there are certain guys that are still very, very good at what they do regardless of their age. And that's where I think we are with those particular guys."

Individually, each player still looks to be in good form. But collectively, they prompt some concern over the age of this defense.

No NFC team made the playoffs last year with four 30-year-olds starting on defense (according to depth charts the first week of the postseason). The Lions were actually the oldest of the conference's six playoff teams at 27.9 years old.

And their projected starting defense this year is even older, at 28.5 years old heading into the season.

Old defenses fared a lot better in the AFC last year, with four of the six playoff qualifiers starting at least four 30-year-olds. Though it's worth noting the conference champion New England Patriots were one of the two exceptions.

NFC

Cowboys -- One 30-year-old starter on defense; average defensive starter was 26.2 years at start of playoffs

Packers -- Three 30-year-old starters; 27.1 average

Panthers -- Two 30-year-old starters; 25.7 average

Cardinals -- Three 30-year-old starters; 26.5 average

Seahawks -- One 30-year-old; 27.2 average

Lions -- Three 30-year-old starters (C.J. Mosley, James Ihedigbo, Rashean Mathis); 27.9 average

AFC

Patriots -- Two 30-year-old starters; 27.1 average

Ravens -- Four 30-year-old starters; 27.4 average

Bengals -- Four 30-year-old starters; 28.1 average

Steelers -- Four 30-year-old starters; 28.2 average

Colts -- Four 30-year-old starters; 28.5 average

Broncos -- One 30-year-old starter; 26.5 average

Detroit's age issues are complicated by the fact it has two fewer draft picks this year, after sending the team's fourth- and fifth-round selections to the Ravens in the Ngata trade. That's two fewer opportunities to get younger.

"You definitely want to build through the draft, and have some young guys in the pipeline coming up," Mayhew said.

That puts more importance on developing the young players already on the roster.

"This coaching staff has done a phenomenal job developing guys," Mayhew continued. "We saw the improvement from Darius Slay last year, and Corey Fuller last year. So I think this coaching staff is great at doing that."

Caldwell has been around a lot of veteran teams, dating to his days with the Colts and then the Ravens. He proved last year, when Detroit went 11-5, that he knows how to get the most out of a veteran team.

Part of his formula includes shortening practice times, which helps keep players fresh into the latter parts of the season.

"I've been on some teams where we've probably a fairly decent number of players in that (30-and-over) range," Caldwell said. "There is a way in which you have to make certain you manage them as well. I think your practices have to be conducive to them.

"There is a wear and tear that occurs in this game, and it's difficult, and it's challenging. It stresses them. So you have to make sure you take those things into account when you're looking at practice duration for those particular individuals. Offseason, all that stuff."

While Jim Schwartz's practices were regularly around two hours, Caldwell often ended his at around 90 or 100 minutes according to players. And he rarely held intense workouts on back-to-back days -- something his predecessor often did, which caused some players to fatigue more quickly.

Veteran players have gushed about Caldwell's ability to keep them fresh throughout the season.

"That's been a major point of emphasis -- keeping us fresh," defensive tackle C.J. Mosley said last year. "Our core team is the same (in 2014), but just being fresher going into everything.

"When we're done with the work, we're done. His whole thing is, 'Take care of me, and I'll take care of y'all.' That's what it is. And I've seen guys run harder to the ball than I did before (in practice), including myself."

Projected Lions defense (age at start of season):

Defense

DE Jason Jones (29)

DT Haloti Ngata (31)

DT Tyrunn Walker (25)

DE Ezekiel Ansah (26)

OLB DeAndre Levy (28)

MLB Stephen Tulloch (30)

OLB Tahir Whitehead (26)

CB Darius Slay (24)

CB Rashean Mathis (35)

SS James Ihedigbo (31)

FS Glover Quin (29)

Offense

WR Golden Tate (27)

WR Calvin Johnson (29)

LT Riley Reiff (26)

LG ???

C Travis Swanson (24)

RG Larry Warford (24)

RT LaAdrian Waddle (24)

TE Brandon Pettigrew (30)

QB Matthew Stafford (27)

RB Joique Bell (29)

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