FRISCO, Texas -- If the Dallas Cowboys are going to make the playoffs in 2021, their offense will have to carry the day, but their defense has to improve over a horrible showing in 2020 in which it allowed the most points in franchise history (473) and second most rushing yards (2,541).

Former Atlanta Falcons coach Dan Quinn has replaced Mike Nolan as coordinator, and he has brought energy and changes to the defense that will better fit the skills of the Cowboys' players.

With training camp starting July 21, are the Cowboys better, worse or the same on defense?

After taking an in-depth look at the Cowboys' offense, here is a position-by-position breakdown of the defense for 2021:

Defensive end

Additions: Tarell Basham, Brent Urban, Chauncey Golston, Austin Faoliu

Losses: Aldon Smith, Breeland Speaks, LaDarius Hamilton

Returners: DeMarcus Lawrence, Randy Gregory Bradlee Anae, Dorance Armstrong, Ron'Dell Carter

Better, worse or the same? Same. But that doesn't mean there isn't room for optimism. Maybe it helps having Quinn, a defensive line coach at heart, on staff to feed that positivity.

Or, maybe it's seeing Gregory go through an offseason program for the first time since his rookie season. Even without much practice time or game time because of suspensions, Gregory has shown to be a natural pass-rusher. With a full season under his belt, perhaps Gregory is an eight-sack-a-season player or more.

While he should be judged by more than sacks, Lawrence has to have more than 6.5 sacks for this defense to improve. Basham and Urban have not had more than 3.5 sacks in a season. The Cowboys are hoping both can achieve more than that with larger roles under Quinn.

Defensive tackle

Additions: Carlos Watkins, Osa Odighizuwa, Quinton Bohanna

Losses: Tyrone Crawford, Antwaun Woods

Returners: Trysten Hill, Neville Gallimore, Justin Hamilton

Better, worse or the same? Same, but it's a little like defensive end. The Cowboys were hoping Dontari Poe and Gerald McCoy would bring some playmaking experience to Dallas given their extensive pro careers. But McCoy suffered a quadriceps injury in camp and never played a game; Poe was ineffective before his release after seven games.

Crawford's professionalism and versatility will be missed. Woods was productive but did not fit what Quinn wants in the spot (size and more size) and was cut in the offseason. Hill is coming back from a torn ACL and the Cowboys still have hope for him, but they believe Gallimore, who is entering his second season, Odighizuwa and Bohanna can help immediately. Urban will play some defensive tackle, and Watkins is a wild-card who will be worth watching when the pads come on.

Linebacker

Additions: Micah Parsons, Keanu Neal, Jabril Cox, Anthony Hines III

Losses: Sean Lee, Joe Thomas, Justin March,

Returners: Leighton Vander Esch, Jaylon Smith, Luke Gifford, Francis Bernard, Azur Kamara

Better, worse or the same? Better. At least they have to be better when Dallas spends its first-round pick on a linebacker like Parsons.

But there are some key ifs. Mainly, can Vander Esch stay healthy and can Smith find his form from 2018? If so, then this defense will be much better. Neal is making the move to the weakside spot but could move back to safety, where he excelled in Atlanta under Quinn.

Parsons will play multiple spots with the Cowboys entering camp thinking he can be a designated pass-rusher from the beginning. Cox was considered one of the best cover linebackers in the draft, but his role might be greater next season than in 2021.

Cornerback

Additions: Kelvin Joseph, Nahshon Wright

Losses: Chidobe Awuzie, Saivion Smith, Chris Westry

Returners: Trevon Diggs, Jourdan Lewis, Anthony Brown, Reggie Robinson II, C.J. Goodwin, Maurice Canady, Deante Burton, Rashard Robinson

Better, worse or the same? Better. The big bet is Diggs will be better in his second season after leading the Cowboys in picks (3) in 2020 as a rookie. Lewis is a solid slot corner and Brown is often overlooked.

Joseph, the Cowboys' 2021 second-round pick, will get the opportunity to show what he can do in the preseason to potentially land the other starting spot opposite Diggs. Wright, a 2021 third-round pick, might need time to develop, but he showed in the offseason work he can make some plays.

As always, the better the pass rush, the better this group will be.

Safety

Additions: Damontae Kazee, Jayron Kearse, Israel Mukuamu, Tyler Coyle

Losses: Xavier Woods

Returners: Donovan Wilson, Darian Thompson, Steven Parker

Better, worse or the same? Same. Will Neal move back to safety? Is Kazee, who is coming back from a torn Achilles tendon, ready to be a full-time player again? Can Wilson, who showed some promise in a lost season a year ago, develop?

Thompson can be a spot starter but is mostly a special-teamer. Kearse has been in a similar role in his career. Mukuamu is moving from corner to safety as a rookie.

This spot has been shaky for the Cowboys for the better part of a decade and these players will have to prove they have the answers.