Detroit Lions head coach Matt Patricia said he wants his team to follow three main principles moving forward. He wants them to be able to run the ball with some consistency, stop the run on defense and cover kicks on special teams.

When it comes to stopping the run, he's going to need enough talent and depth in the middle of the defensive line to get the job done.

A'Shawn Robinson returns to hold down one of the defensive tackle spots. We'll see if he's joined by fellow starter and veteran Haloti Ngata, who is an unrestricted free agent. Before Ngata injured his bicep Week 5 and was lost for the season, Detroit was allowing 74.6 yards per game on the ground. Without him, that number ballooned to 129.7 the rest of the way.

Key reserve Akeem Spence also returns, but even if Ngata is back, the Lions could stand to add another player or two to that interior group via free agency or the NFL Draft.

Here's a primer on some of the defensive tackles to get familiar with ahead of the NFL Scouting Combine later this month:

VITA VEA

School: Washington

Ht/Wt: 6-4, 344

Best trait: Power. Time and again in college he dominated centers and guards when isolated on just one. He also has terrific feet and can move very well for a man his size. He was a running back in high school. He's a space eater that should instantly improve a team's run defense.

Concern: He's not a polished pass rusher. He's a space eater and run stopper, and anything teams get via the rush is a bonus at this point.

Skinny: He's a big powerful tackle that probably better fits as a nose tackle than a three-technique in the NFL.

MAURICE HURST

School: Michigan

Ht/Wt: 6-2, 282

Best trait: Disruptor. He might have the best first step of any of the tackles in this class. He made a living playing in the opponent's backfield while at Michigan. He had 13 tackles for loss and 5.5 sacks last season from the interior.

Concern: He's on the smaller side for an interior defender. Will his quickness be able to counter big, strong, mauling guards in the NFL?

Skinny: He's a true three-technique tackle that can excel in an aggressive scheme that asks him to blow off the ball and use his quickness to get up the field.

DA'RON PAYNE

School: Alabama

Ht/Wt: 6-2, 308

Best trait: Strength. He has tremendous strength and knows how to leverage it to manipulate offensive linemen. He's also a terrific athlete, which is a dangerous combination for an interior defender. He recorded 53 tackles from the interior with a sack, an interception and three passes defended.

Concern: He needs to improve his pass-rushing repertoire. More and more in the NFL's pass-heavy game, interior defenders have to better perfect that aspect of their game.

Skinny: He steps in right away and makes a defense better against the run. If his pass-rushing skills come along quickly, he can be a true impact player from the interior.

TAVEN BRYAN

School: Florida

Ht/Wt: 6-4, 291

Best trait: Penetrator. Bryan shows off some defensive end traits because of his agility and quickness. He recorded four sacks from the interior last year, and has terrific speed to chase down plays on the back side.

Concern: Because his frame is built for speed and explosiveness, he's not as powerful as some of the other interior defenders in this class. Also, the overall production doesn't fit the athletic traits.

Skinny: He has a rare skillset for an interior defender that might actually fit well in the NFL as a get-to-the-quarterback player. He's got a high ceiling, but it might take some time for him to reach his true potential.

HARRISON PHILLIPS

School: Stanford

Ht/Wt: 6-3, 303

Best trait: Production. Amazingly, he led Stanford with 98 tackles and 17 tackles for loss, and also chipped in 7.5 sacks. That's some kind of production from the interior. A former high school national champion wrestler, the ability to manipulate opponents and use leverage to make plays shows up often with Phillips.

Concern: He's not a terrific athlete. He's more of a scrapper than anything else. How will he perform against bigger and more technically sound NFL interior offensive linemen?

Skinny: Phillips might not wow people with his physical traits at the Combine later this month, but football is about production, and he has a ton of it. He understands the game, and has a nose for the football. That should count for something.