With free agency set to begin in mid-March, Redskins.com previews the 2019 NFL free agent class position-by-position. Today's focus starts with the defensive linemen.

For the Redskins, this is a position group that looks pretty strong entering the 2019 season, and one that likely doesn't need to add a veteran. That's primarily because of the four players under rookie contracts that made significant strides as a unit last season.

Alabama products Jonathan Allen and Daron Payne, Matt Ioannidis and Tim Settle all return with varying degrees of experience and production under their belts. The Redskins also return Caleb Brantley, whom they signed at the beginning of last season, and veteran Stacy McGee, who missed the first half of the year on the PUP list.

Here's a look at the top five free agents at ths position, along with more below.

Grady Jarrett, Falcons

Coming off of playing in 14 games as a starter for Dan Quinn's Atlanta Falcons, Jarrett set career highs in sacks (six) and quarterback hits (16) while recording 16 tackles. Jarrett's best game came in Week 15 against the Arizona Cardinals when he recorded two sacks, seven tackles, and two quarterback hits.

Jarrett played sparingly in his rookie season, starting just two games while recording one sack in 2015. The defensive tackle saw regular playing time in 2016, recording three sacks and 48 tackles in 14 starts. However, Jarrett had the game of his life in Super Bowl LI against the New England Patriots, recording three sacks, helping Atlanta jump out to a 28-3 lead.

Jarrett has compiled 14 sacks, 40 quarterback hits, and 179 tackles throughout his young career. The agile defensive tackle prides his game on beating double teams against both the run and the pass, and has solidified himself as one of the top young defensive tackles in the NFL.

Sheldon Richardson, Vikings

The 6-foot-3, 295-pound Richardson was selected by the New York Jets with the No. 13 overall pick in 2013 that they acquired in the trading away of cornerback Darrelle Revis to the Tampa Bay Buccaneers.

His time with the Jets was well spent as he made the Pro Bowl in 2014 and played a variety of roles on the New York defense. He was traded to Seattle in 2017 and started in all 15 games he played there for Pete Carroll's Seahawks. After joining the Vikings on a one-year deal last offseason, he finished the year starting in all 16 games adding 4.5 sacks on the year.

Richardson has proved his fit with the Vikings this season as a running mate inside with Linval Joseph but would add a veteran presence along a Washington 3-4 defensive front that touts the likes of Daron Payne at defensive tackle.

Michael Pierce, Ravens

An undrafted free-agent out of Samford in 2016, Michael Pierce has become one of the bright young nose tackles the 2019 NFL free-agency class has to offer.

After starting in just one game in 2016, Pierce was so impressive in the flashes he presented, the team felt comfortable enough to deal Timmy Jernigan to the Philadelphia Eagles.

The rest is history. Pierce would go on to start 13 games in 2017 (played in all 16), and notched 49 tackles with one sack from his nose tackle position.

He played in 13 games in 2018 (starting two), adding 20 tackles, four tackle for loss, and one fumble recovery.

Now headed into 2019 and the free agency period, Pierce will look to continue to improve his game while he explores options and gauges interest from around the league.

David Irving, Cowboys

David Irving, who is still only 25 years old, signed as an undrafted free agent with the Chiefs in 2015 and was placed on the team's practice squad.

The Cowboys signed him away to their active roster only a few weeks into the season and he was a rotational lineman by midseason. From there, Irving's stock began to bloom with four sacks and 15 quarterback hits in 2016 and 7 sacks in 8 starts for the Cowboys in 2017.

The towering 6-foot-7 Irving was dominant down the stretch in 2016, and proved it wasn't a fluke the year after. He was limited to just eight games because of a concussion and a suspension in 2017, but was terrific in those eight contests, registering seven sacks.

Irving only played in two games in 2018 because of injury, and was recently suspended indefinitely for another substance abuse violation.

Muhammad Wilkerson, Packers

Before joining the Packers, Wilkerson visited many teams after the 2017 season, including a visit to Redskins Park to meet with Jay Gruden.

Wilkerson played for the Jets from 2011-2017, and has been named to the All-Pro team twice and to the Pro Bowl once in 2015. However, his last two seasons have been below his performance standard, recording 4.5 sacks in 2016 and 3.5 sacks in 2017, compared to his 18.0 combined sacks in the 2014-2015 seasons.

Packers current defensive coordinator Mike Pettine was Wilkerson's defensive coordinator for two seasons in New York and has helped Wilkerson improve his game which led to him recording 10.5 sacks in 2013 and 12 sacks in 2015. However, the Redskins defensive line is coached by Jim Tomsula, who has gained the respect as one of the top D-line coaches in the NFL.

In his career, Wilkerson has recorded 498 tackles (324 solo), 44.5 sacks, two interceptions, 26 passes defended, 10 forced fumbles and a fumble recovery that he returned for a touchdown in 101 career games.

Other notable free agent defensive linemen: Christian Covington, Darius Philon, Johnathan Hankins, Danny Shelton, Bennie Logan