Big-time NFL free agency and the 2014 Draft are in the books. Some teams tried to fill holes with their offseason acquisitions and draft picks. Some teams doubled down on their strengths. At this point, it's reasonably safe to look forward at projected NFL rosters and depth charts to get an idea of the major contributors at each positional group, and while doing this, one can start to piece together where teams are strongest, deepest, most talented, and conversely where they're thin or threatened.

To take stock of where rosters stand, it makes sense to look at the teams that are among the NFL's best at each positional group.

First up: the defensive line.

Note that for this exercise, I'm not sticking to the letter of the law when it comes to actual "defensive line" positions because 3-4 outside linebackers and 4-3 defensive ends can have similar roles while playing in different schemes. In this case, I've included both, and consider players that primarily line up near the line of scrimmage and/or frequently rush the passer as "defensive linemen." It's probably a little ambiguous and this list may crossover a little with the rankings of linebacker corps, but hopefully you'll get the idea.

Further, I included 18 NFL clubs on my list of defensive lines, all teams with the most realistic shot at being the NFL's best defensive line in 2014. That said, I'm sure I overrated, underrated, or forgot about a couple teams with strong defensive lines within my list.

Here goes ...

The elite

In my eyes, there are two teams that stand out above the rest when it comes to sheer talent and depth on the defensive line going into 2014, and both are in the NFC: St. Louis and Carolina.

DE Robert Quinn, DE Chris Long, DT Michael Brockers, DT Kendall Langford, DE Eugene Sims, DE Williams Hayes, DT Aaron Donald, DE Michael Sam, DE Ethan Westbrooks

The Rams' formidable defensive line features probably the best young defensive end in the NFL right now in Robert Quinn, who racked up 19.0 sacks in 2013, and opposite him, they feature veteran pass-rusher Chris Long, who added a not-too-shabby 8.5 himself last year. These two bookended the talented Michael Brockers (5.5 sacks) and Kendall Langford (5.0 sacks), and now St. Louis adds the guy who was probably the best pure interior pass-rusher in the draft this year in Aaron Donald. Scary.

Robert Quinn, Photo credit: Otto Greule Jr

Bottom line, opposing quarterbacks will quake at the thought of the Rams' nickel defensive line group featuring Quinn, Brockers, Donald and Long. Who do you focus on? Who do you scheme for? Good luck.

DE Charles Johnson, DT Dwan Edwards, DT Star Lotulelei, DE Greg Hardy, DT Kawann Short, DE Frank Alexander, DT Colin Cole, DT/DE Kony Ealy

The defensive line is Carolina's heart and soul, and the rotation featuring Charles Johnson, Star Lotulelei, Dwan Edwards, Greg Hardy and Kawann Short last year had the ability to take over games and dominate opposing offenses. The Panthers racked up 60 sacks in 2013 (1st in the NFL) while holding opposing teams to a paltry 86.9 yards rushing per game (2nd in NFL) and allowing a league-low four rushing touchdowns.

Making things a little more interesting there, Carolina drafted the dynamic and versatile Kony Ealy with the 60th overall pick. Ealy, who was considered by many as a first-round talent, should factor in on nickel downs as both an outside and inside pass-rusher and find himself with a lot of one-on-one matchups as teams focus on all the other scary-ass pass-rushers already on the line.

The combination of devastatingly talented, proven returning starters with highly-rated, potentially high-impact draft picks give the Rams and Panthers the two defensive lines going into next season. The next group is very, very close behind.

The damn good

DE Muhammed Wilkerson, DT Damon Harrison, DE Sheldon Richardson, OLB Quinton Coples, DT Kenrick Ellis, DE Leger Douzable, DE Zach Thompson, DE IK Enemkpali

Leaving the Jets off the "elites" list wasn't easy, and the only reason Carolina and St. Louis separated themselves to me is because of their infusion of talent via the draft. The Jets remain a powerhouse on the defensive line, and feature the dynamic and nearly unstoppable Mo Wilkerson (10.5 sacks in 2013), the underrated Damon Harrison (Pro Football Focus' top-rated run-stopping defensive tackle last year), and the AFC's Defensive Rookie of the Year in Sheldon Richardson (excellent as a run-stopper and pass-rusher). With former first-rounder Quinton Coples and the powerful Kenrick Ellis in the mix, the Jets are multiple, versatile, and tough up front, and give Rex Ryan some incredible tools with which to work.

The Jets were arguably the best run defense in the NFL in 2013, allowing a league-low 3.4 yards per carry and a third-ranked 88.2 yards per game, and there's no reason to believe they'll regress in 2014. In fact, it's probable they are even more fearsome with the further development of Wilkerson, Richardson, Harrison and Coples.

DT Ndamukong Suh, DT Nick Fairly, DE Jason Jones, DE Ziggy Ansah, DE Devin Taylor, DT C.J. Mosley, DE Darryl Tapp, DT Vaughn Martin, Caraun Reid, Larry Webster, Kyle Van Noy

You really can't talk about defensive lines without bringing up the Lions, who have invested heavily (via the draft) in the trenches during the past several years. Suh remains a force; he was second only to Tampa Bay's Gerald McCoy in Pro Football Focus' pass-rush productivity rating in 2013, registering an incredible 54 quarterback hurries to go with his 5.5 sacks. Nick Fairly was no slouch either, collecting 6.0 sacks and 41 quarterback hurries, and last year the rookie Ziggy Ansah got off to a solid start with 8.0 sacks and 22 hurries.

For depth, another rookie in Devin Taylor showed some promise in his first year, and the veteran Jason Jones will return from a knee injury that limited him to three games in 2013 and provide a spark both outside and on the interior as a nickel rusher. The Lions also drafted one of the more intriguing three-technique pass-rushing defensive tackles in the draft in Caraun Reid, and picked up the versatile Kyle Van Noy and the raw but promising Larry Webster.

NT Terrance Knighton, DE Derek Wolfe, DT Sylvester Williams, DE Demarcus Ware, OLB Von Miller, DE Malik Jackson, DT Kevin Vickerson, DE Quanterus Smith

The Broncos have one of the most disruptive and immoveable nose tackles in the NFL in Terrance "Pot Roast" Knighton, and have added to their trenches with the additions of Wolfe and Williams over the last couple of seasons. Wolfe battled injuries all last year, but projects to get back onto the gridiron in 2014, and Williams, Denver's 2013 first-round pick, will add toughness, physicality and a quick first step to that line. In addition to excellent depth in Jackson (6.0 sacks in 2013) and Vickerson, the Broncos are going all-in for next season with the acquisition of the inimitable Demarcus Ware, a potential game-changer.

Oh, and let's not forget about Von Miller, who is listed as an outside linebacker, but frequently and effectively rushes the passer in Denver's defense. Miller is coming back from an ACL tear in 2013, but if healthy, when combined with Wolfe, Ware, Williams, Jackson and Knighton, will give the Broncos very, very interesting options on defense.

DT Marcel Dareus, DT Kyle Williams, DE Mario Williams, DE Jerry Hughes, DT Alan Branch, DT Stefan Charles

The Bills, perhaps somewhat quietly, finished second in the NFL in sacks in 2013 with 57.0, and their core group of Dareus, Williams, Williams, Branch and Hughes is among the most destructive in the NFL while rushing the passer. The depth behind those five is somewhat tenuous, but with luck in the health department, Buffalo will continue to get after quarterbacks with success.

NT Haloti Ngata, DT Brandon Williams, OLB Terrell Suggs, OLB Elvis Dumervil, OLB Courtney Upshaw, OLB Pernell McPhee, DE Chris Canty, NT Terrence Cody, DT/DE Kapron Lewis-Moore, DT/DE Timmy Jernigan, DT/DE Brent Urban

What can you say about the Ravens' defensive line group that hasn't already been said? Tough, deep, versatile, intimidating. Ozzie Newsome has an experienced and savvy veteran group with Ngata, Suggs, Dumervil and Canty that is augmented by Upshaw, McPhee, Lewis-Moore, and a couple of excellent picks from this year's draft, in my opinion, in Jernigan and Urban. This group will have no issue perpetuating Baltimore's reputation as a perennial defensive dreadnaught.

Contenders for the crown

I didn't know what else to label this next tier, because frankly some of them probably deserve to be ranked higher. I had to come up with some sort of order, though, but these next few teams are both deep and talented along the defensive line.

DE Jarvis Jenkins, DT Barry Cofield, DE Jason Hatcher, OLB Ryan Kerrigan, OLB Brian Orakpo, DE Kedric Golston, DE Trent Murphy

The Redskins added DT/DE Jason Hatcher (11.0 sacks in 2013) to a line that already included the underrated Barry Cofield, the disruptive Ryan Kerrigan, and the elite Brian Orakpo. Adding the versatile Trent Murphy into the mix should be interesting to watch. Overall, that's a lot of pass-rushing weaponry in Washington, and they're a team that played the run fairly well in 2013.

DE Ahtyba Rubin, DT Phil Taylor, DE Desmond Bryant, OLB Paul Kruger, OLB Jabaal Sheard, OLB Barkevious Mingo, OLB Quentin Groves, DE John Hughes, DE Billy Winn, NT Ishmaa'ily Kitchen, DE Armonty Bryant

This is a very deep and versatile group in Cleveland, and while the Johnny Manziel experience might be what many fans talk about with regard to the Browns in 2014, I'd expect that the defense will be the identity of the franchise. With Taylor, Bryant, Kruger, Sheard, Mingo and others, Cleveland has talent in the trenches and edges.

OLB Junior Gallette, DE Cameron Jordan, NT Brockrick Bunkley, DE Akiem Hicks, DE Glenn Foster, OLB Parys Haralson, OLB Victor Butler, NT John Jenkins, DE Rufus Johnson, OLB Ronald Powell, DE/DT George Uko, OLB/DE Chidera Uzo-Diribe, OLB/DE Kasim Edibali

Cameron Jordan, Photo credit: Howard Smith-USA TODAY Sports

Junior Gallette (12.0 sacks) and Cameron Jordan (12.5) combined to become one of the best pass-rushing duos in the NFL last year, and New Orleans' depth does not end there. Hicks, Foster, Haralson and Butler all could be impact players in 2014, and the Saints added a few mid-to-late-round picks with potential in Powell, Uko, Uzo-Diribe, and Edibali. Upside, speed, nice athleticism and get-off. Rob Ryan's defense has some very good depth on the line.

Calais Campbell, Dan Williams, Darnell Dockett, John Abraham, Matt Shaughnessy, Alameda Ta'amu, Frostee Rucker, Kareem Martin, Ed Stinson

The Cardinals had one of the best defenses -- maybe the best defense -- in the NFL last year, and their dominance started up front. Campbell, Dockett, Williams, and Abraham hold it down, and are supported by Shaughnessy, Ta'amu and Rucker. I liked their picks in the high-potential Kareem Martin and steady-but-underrated Ed Stinson, both excellent run-defenders in college. Arizona will be very, very difficult to run against in 2014, and their pass-rush is no joke either.

NT Dontari Poe, DE Mike DeVito, DE Allen Bailey, OLB Tamba Hali, OLB Justin Houston, DE Vance Walker, NT Jaye Howard, OLB Dee Ford

The Chiefs also had an elite defense in 2013 and Poe, Hali and Houston starred. Throwing quick-off-the-snap Dee Ford into the mix should be extremely interesting.

Revamped

A couple of teams changed their defensive lines significantly during the offseason, so the best we can do right now is project for 2014. The two that improved vastly, on paper, were Chicago and Atlanta.

DT/DE Lamarr Houston, DT Jay Ratliff, DT Stephen Paea, DE Jared Allen, DE Willie Young, DE Cornelius Washington, DT Ego Ferguson, DT Will Sutton

The Bears, coming off a season in which they gave up a league-high 5.3 yards per carry to opposing ball carriers while notching a league-low 31.0 sacks, added three of the top defensive line free agents this offseason in Houston, Allen and Young. To show the world that they mean business when it comes to improving in the trenches, they then went out and drafted a couple more potential impact players in Ferguson and Sutton. It's hard not to like what Chicago has done to improve competition, depth, and talent on their line, and they should almost surely improve drastically in 2014.

NT Paul Soliai, DE Tyson Jackson, DE Jonathan Babineaux, OLB Kroy Biermann, DE Malliciah Goodman, OLB Osi Umenyiora, DE Corey Peters, OLB Johnathan Massaquai, DT/DE Ra'Shede Hageman, OLB Tyler Starr

Atlanta's offseason acquisition list continues to point toward a more hybrid 4-3/3-4 defense, which makes them one of the more interesting teams to watch on defense this year. In addition to picking up Soliai and Jackson in free agency, they grabbed one of the most boom-or-bust prospects in the draft in Ra'Shede Hagemen. If a hybrid, multiple front is what the Falcons want in 2014, Hageman is a pretty perfect fit for that, able to line up at the five-technique defensive end spot as well as he can inside at the three-technique.

Wild cards

DT Gerald McCoy, DT Akeem Spence, DT/DE Williams Gholston, DE Michael Johnson, DE Adrian Clayborn, DE Da'Quan Bowers, DT Clinton McDonald, DT Everett Dawkins, DE Steven Means

The Bucs look great on paper going into 2014. McCoy is a proven, elite impact player, and Tampa Bay added Michael Johnson and Clinton McDonald in free agency. Adrian Clayborn and Da'Quan Bowers will have the chance to live up to their high-billing and Spence, Gholston and Means show promise. In terms of potential on the defensive line, Tampa Bay might be the team to watch next season.

DT/DE J.J. Watt, OLB Brooks Reed, OLB Whitney Mercilus, DE Tim Jamison, DE Jared Crick, OLB Jadeveon Clowney, NT Louis Nix, DE/DT Geoffrey Pagan.

The Texans have J.J. Watt, one of the most absurdly disruptive defensive players in recent memory and quite possibly the future Defensive Player of the Year for 2014. Oh, and they just added Jadeveon Clowney at OLB/DE and a first-round talent in Louis Nix at NT. Despite the fact that they lost Antonio Smith and Earl Mitchell in free agency, this is a team that I really can't wait to watch on defense.

Question marks

OLB Aldon Smith, DT Ray McDonald, DT Glenn Dorsey, DT Justin Smith, OLB Ahmad Brooks, DE Tony Jerod-Eddie, DT Ian Williams, DE Demarcus Dobbs, DT/DE Quinton Dial, DT/DE Tank Carridine, OLB Corey Lemonier, OLB Aaron Lynch.

I look at the Niners' defensive line group and see a cadre of elite players in Justin Smith, Ahmad Brooks and Aldon Smith, an extremely solid core in Dorsey, McDonald, Jerod-Eddie, Williams, Dobbs and Dial, and a couple of high-potential question marks in Carradine, Lemonier and Lynch. The question mark for this year, though, is what will happen with Aldon Smith. If Smith is on the field, you might put the Niners in the elite category because he's one of the most unstoppable pass-rushers in the NFL. If he's not there, San Francisco takes a hit, and their depth will be tested. In addition to Smith's status, Carradine and Lynch in particular should be interesting to watch this year as well.

DT Brandon Mebane, DT Tony McDaniel, DT/DE Michael Bennett, DE Cliff Avril, DE/OLB Bruce Irvin, DT Jesse Williams, DT Jordan Hill, DT Greg Scruggs, DE Benson Mayowa, DT D'Anthony Smith, DT/DE Cassius Marsh, DT Jimmy Staten, DE Jackson Jeffcoat

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The Seahawks had Pro Football Focus' first-ranked pass-rush in 2013 by a long shot, and PFF's fifth-ranked run defense, so you know they're doing something right on their D-line. That said, they released veterans Red Bryant and Chris Clemons and lost Clinton McDonald in free agency, so there's a large amount of uncertainty in that position group going forward.

Like San Francisco, Seattle has some high-potential yet untested players to plug in in Jordan Hill, Jesse Williams and Greg Scruggs, and have yet to really establish Bruce Irvin's ceiling as a pass-rusher. Seattle did themselves a favor by re-signing Michael Bennett, and putting him on a line with Brandon Mebane, Tony McDaniel and Cliff Avril makes for a nice starting front four. Still, of course, there are some question marks going forward for the Super Bowl champs.

I'm not going to pretend I got all these spot on, so in the comments below, let me know where you differ in opinion or let me know where I missed the mark.