The bulk of NFL free agency is in the rearview mirror, which means we have a much better feel for the teams that will be contenders during the 2020 season. Yes, the NFL draft will have an impact, but that process is a bit of a crapshoot and we shouldn't be making drastic changes to our short-term expectations for teams with the assumption of major contributions from first-year players.

With that, here are five teams that have improved their stock the most by making the right moves this offseason. Be sure to also check out a complete look at post-free agency leaguewide unit grades.

Biggest upgrade (unit): Interior defensive line -- Just prior to last season, I ranked Dallas' defensive interior last in the league. The Cowboys seemingly agreed with that assessment as they recently signed one of the league's top defensive tackles over the past decade, Gerald McCoy, and run-stuffer Dontari Poe as running mates for Tyrone Crawford. McCoy and Poe combined for 9.0 sacks last season. The rest of the returning Dallas roster combined for 17.5. This is now a borderline top-10 unit.

Biggest upgrade (player): Ha Ha Clinton-Dix -- Dallas' safety situation has been yet another major concern area -- it ranked 30th in the 2019 unit grades -- so the addition of a reliable and perhaps underrated safety, Clinton-Dix, is significant. He and FS Xavier Woods supply Dallas with what is now a solid duo at the position.

Underrated addition: Greg Zuerlein -- The longtime Rams kicker is coming off a down season in which he hit only 24 of 33 kicks (72.7%), though he was much better the prior three seasons (89.3%). Meanwhile, Dallas kickers have posted a conversion rate below 79% each of the past three seasons. Zuerlein is an obvious upgrade.

Weakest link: Tight end -- Dallas is pretty solid across the board, but we can pick on tight end a bit following the departure of Jason Witten. Blake Jarwin is a candidate for a leap, but he's thus far been no more than a situational player through three pro seasons. Dalton Schultz and Blake Bell are his backups.

Bottom line: The likes of Witten, center Travis Frederick, cornerback Byron Jones and receiver Randall Cobb are gone, but Dallas countered that with improvements at key positions. The roster looks solid or very good at nearly every position, which makes quarterback Dak Prescott's squad a strong contender for the NFC East crown.

Biggest upgrade (unit): Quarterback -- I'm cheating here since the Steelers' offseason has been fairly quiet thus far, but getting Ben Roethlisberger back from injury is the key reason to vault this team into legitimate contender status. Incredibly, Pittsburgh went 8-8 last season despite a horrific offensive performance that saw the team score a grand total of 10 touchdowns during its final nine games. The Steelers scored 51 offensive touchdowns (fifth most) with Roethlisberger in 2018.

Biggest upgrade (player): Eric Ebron -- The former Indianapolis Colts tight end is coming off an underwhelming and injury-plagued 2019 campaign, but we saw his upside when he posted a 66-750-13 receiving line with Andrew Luck in 2018. The 27-year-old is a clear upgrade on Vance McDonald, who has yet to stay healthy for a full 16-game regular season.

Underrated addition: Chris Wormley -- Wormley, the former Baltimore Ravens defensive end, isn't a big name and will operate as a role player, but he'll help replace the team's only significant defensive loss, Javon Hargrave. Pittsburgh will have back a majority of a defense that ranked no lower than fifth in interceptions, forced fumbles, sacks (No. 1 each of the past three seasons), tackles for loss, yards allowed and points allowed last season.

Weakest link: Running back -- If running back is your weak link, you've probably done a nice job building a roster. A healthy and reliable James Conner would boost the grade, but the Steelers seem likely to address the position during the draft.

Bottom line: Pittsburgh is loaded. The defense was elite in 2019 and nearly the entire group will be back this season. Roethlisberger, who led the NFL in passing in 2018, is back along with an above-average line and intriguing, young wide receiver trio led by JuJu Smith-Schuster, Diontae Johnson and James Washington. Expect this team to push Baltimore for the AFC North crown.

Biggest upgrade (player): Tom Brady -- No shocker here. Sure, Brady and his predecessor in Tampa, Jameis Winston, had the exact same QBR last season, but that was far from the usual for the GOAT. Where Winston constantly put the Buccaneers in tough spots with 30 interceptions last season, Brady has thrown a total of 29 interceptions over the past four seasons.

Biggest upgrade (unit): The defense as a whole -- There are two pieces to this: re-signings and the progression of young players. Even prior to the Brady signing, the Buccaneers had the look of an ascending team, so the re-signing of defensive linemen Ndamukong Suh and Jason Pierre-Paul and linebacker Shaquil Barrett can't be overlooked when evaluating their offseason. Further development from Devin White (2019 first-round pick), Vita Vea (2018 first-rounder), Carlton Davis (2018 second-rounder), Sean Murphy-Bunting (2019 second-rounder), Jamel Dean (2019 third-rounder) and Mike Edwards (2019 third-rounder) also will help. Add in standout LB Lavonte David and Justin Evans' return from a foot injury and you have a defense that could take a big leap in 2020.

Underrated addition: Joe Haeg -- This one is a bit of a reach, but Tampa Bay surely isn't done adding to the right side of its offensive line. Haeg at least gives the Bucs a veteran presence at right tackle for the time being.

Weakest link: Safety and running back -- There are no sure bets in this safety group, but at least they have options. Edwards, Evans, Jordan Whitehead and Andrew Adams will compete for the bulk of the snaps. Lead back Ronald Jones II took a leap in 2019, but the Buccaneers are a strong bet to add a pass-catching back in the draft.

Bottom line: If you correctly weigh positional importance, it's not crazy to suggest that the Buccaneers have a borderline top-five roster. There's Brady under center, an elite duo at wide receiver (Mike Evans and Chris Godwin), an imperfect but competent offensive line, a terrific front seven and an ascending secondary. Tampa Bay is a strong NFC wild-card contender.

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Mike Wells previews what a Philip Rivers and Frank Reich team looks like, but admits Rivers isn't a long-term solution at QB, suggesting the Colts keep an eye out for Jalen Hurts in the upcoming draft.

Biggest upgrade (unit): Quarterback -- The Colts basically had no choice but to put all of their eggs in the Jacoby Brissett basket following Andrew Luck's shocking retirement last August. That didn't work out, but they found a short-term upgrade by signing Philip Rivers in the offseason. Yes, Rivers isn't coming off his best NFL season, but he was competent, ranking 11th in completion percentage and yards per attempt. The 38-year-old still has some life.

Biggest upgrade (player): DeForest Buckner -- Colts GM Chris Ballard said that the team's defensive scheme runs through the 3-technique, so landing a star at the position in Buckner is huge for this unit. The 26-year-old was arguably the 49ers' best player during their 2019 Super Bowl run. The Colts also added Buckner's ex-teammate Sheldon Day to a group that includes Denico Autry, Grover Stewart and edge/DT Tyquan Lewis.

Underrated addition: Xavier Rhodes -- It has been a few years since Rhodes was at the top of his game, but the 29-year-old will no longer face the pressure of operating as a team's clear No. 1 corner. Rhodes joins fellow corners Kenny Moore II, Rock Ya-Sin and T.J. Carrie. Perhaps Rhodes will bounce back in a system that has protected its corners well in recent seasons.

Weakest link: Wide receiver -- T.Y. Hilton is a star, but he's also 30 and has little reliable help. Zach Pascal and Parris Campbell are next up and the only other sure bets to make the 2020 roster.

Bottom line: The Colts have compiled what is arguably a top-five defense with no clear weak spots, as well as an elite offensive line. Their 2020 prospects will surely be defined by what they get out of Rivers, but even a solid campaign from the veteran could be enough to earn the Colts an AFC South title.

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Ben Baby breaks down the Bengals' moves to sign D.J. Reader and Trae Waynes in free agency; both deals combine to be an estimated $95M. Baby then looks to what Cincinnati could do with its No. 1 overall draft pick.

Biggest upgrade (unit): Secondary -- The Bengals have made gigantic strides on defense. It starts with the overhaul at corner, with Dre Kirkpatrick, Darqueze Dennard and B.W. Webb being upgraded to Trae Waynes, Mackensie Alexander and LeShaun Sims behind William Jackson. Vonn Bell replaces Shawn Williams at strong safety to pair with third-year free safety Jessie Bates. At worst, this is a solid secondary.

Biggest upgrade (player): D.J. Reader -- Reader is far from a household name on the defensive line, but the 25-year-old has been an enforcer on the interior for Houston over the past four seasons. Reader joins Geno Atkins to give Cincinnati one of the league's best one-two punches at defensive tackle.

Underrated addition: Josh Bynes -- Bynes is a 30-year-old journeyman on his fifth NFL stop, but, at worst, he has been a consistent role player throughout his eight professional seasons. Bynes has arguably played the best ball of his career over the past two seasons with Arizona and Baltimore and now supplies the Bengals with a much-needed reliable presence at linebacker.

Weakest link: Offense -- While the Bengals made a massive defensive leap, their offense remains a work in progress. The good news is that there is hope. The offensive line is in very rough shape, but 2019 first-round pick LT Jonah Williams will return from injury. The skill positions also are very good when healthy, especially with A.J. Green returning. The best news? The Bengals will have a franchise quarterback in place if they select Joe Burrow with the first overall pick of April's draft.

Bottom line: The Bengals are likely a year away from making the leap to the playoffs, but they're on the right track. Most importantly, they're likely only a few weeks away from drafting a quarterback with franchise-altering upside.