The first wave of free agency is over, and the four teams in the NFC North have to feel pretty good about the additions they've made and how their rosters are starting to shape up as we head to the second wave.

Here's a look at how Green Bay, Minnesota, Chicago and Detroit are looking after the first week of free agency:

GREEN BAY

2019 record: 13-3

Key roster additions: T Rick Wagner, TE Marcedes Lewis, LB Christian Kirksey

Key losses: LB Blake Martinez (New York Giants), T Bryan Bulaga (Los Angeles Chargers), TE Jimmy Graham (Chicago), OLB Kyler Fackrell (New York Giants), ILB B.J. Goodson (Cleveland)

Twentyman: The Martinez loss is more significant than people might think at first glance. He's recorded at least 144 tackles in each of his last three seasons. Bulaga and Fackrell are also significant losses.

The addition of Kirksey should help stem the loss of Martinez, as long as Kirksey gets back to his 2016-17 form when he was a triple-digit tackler in back-to-back seasons. He's only played in nine games total the last two years, however. Wagner fills the place of Bulaga, but it's a little bit of a step down in terms of one-for-one talent.

MINNESOTA

2019 record: 10-6

Key roster additions: DT Michael Pierce, S Anthony Harris (franchise tag), K Dan Bailey (re-sign), P Britton Colquitt (re-sign), T Rashon Hill, QB Sean Mannion (re-sign),

Key losses: CB Trae Waynes (Cincinnati), DT Linval Joseph (Los Angeles Chargers), DE Stephen Weatherly (Carolina), SS Andrew Sendejo (Cleveland), S Jayron Kearse (Detroit), WR Laquon Treadwell (Atlanta)

Twentyman: We knew Minnesota's roster was going to look different in 2020, especially on defense, given their free agent situation, and the fact they entered free agency with not a lot of cap space to work with.

Everson Griffen, who opted out of the remainder of contract, said goodbye to Minnesota on Instagram, so it seems unlikely he'll return. Big loss for the Vikings there. Waynes and Joseph were also starters on defense who will now be playing elsewhere in 2020.

Pierce is a good run stuffer to fill Joseph's spot, but the Vikings still need to find more pass-rushing help after the loss of Griffen.

O'HARA: Daniel looking forward to learning Bevell's offense O'HARA: Shelton heading to Detroit with reputation as a run-stuffing DT TWENTYMAN: A closer look at the 8 players the Lions agreed to terms with

CHICAGO

2019 record: 8-8

Key roster additions: DE Robert Quinn, QB Nick Foles (trade w/ Jacksonville), TE Jimmy Graham, TE Demetrius Harris, S Deon Bush (re-sign), S Jordan Lucas, CB Artie Burns, OLB Barkevious Mingo, LB Danny Trevathan (re-sign)

Key losses: ILB Nick Kwiatkoski (Las Vegas Raiders), QB Chase Daniel (Detroit), OLB Leonard Floyd (Los Angeles Rams), LT Cornelius Lucas (Washington), S HaHa Clinton-Dix (Dallas), OLB Kevin Pierre-Louis (Washington)

Twentyman: Chicago could be onto something with Khalil Mack on one side and Quinn on the other upfront on defense. Quinn had 11.5 sacks last season for the Cowboys, and has 80.5 sacks over nine seasons.

Foles will come in and compete with Mitchell Trubisky for the starting quarterback role, but he might not be a big upgrade over Trubisky, even if he wins the job. He was 0-4 as a starter in Jacksonville last year.

Graham didn't show much in Green Bay last season.

DETROIT

2019 record: 3-12-1

Key roster additions: LB Jamie Collins, OL Halapoulivaati Vaitai, CB Desmond Trufant, QB Chase Daniel, DT Nick Williams, DT Danny Shelton, S Miles Killebrew (re-sign), S Jayron Kearse, CB Tony McRae, S Duron Harmon (trade w/ New England).

Key losses: CB Darius Slay (trade w/ Philadelphia), G Graham Glasgow (Denver), OLB Devon Kennard (Arizona), DT A'Shawn Robinson (Los Angeles Rams), RT Rick Wagner (Green Bay), QB Jeff Driskel (Denver), RB J.D. McKissic (Washington), TE Logan Thomas (Washington).

Twentyman: There weren't as many big splashes in free agency this year as we saw last year with players like Trey Flowers and Justin Coleman, but the Lions focused on getting players that fit their schemes.

Collins is a versatile player and an overall upgrade over Kennard opposite Flowers. Shelton and Williams are big, stout run stuffers in the middle.

Trufant isn't a one-for-one replacement for Slay in terms of pure talent, but he's experienced and has been a No. 1 cornerback in this league for a long time. Daniel improves Detroit's backup situation at quarterback.

Detroit still has to replace Glasgow at right guard.