IRVING, Texas -- The NFL once banned Leon Lett for a year from the game he loved.

It’s one of the best things that ever happened to the Dallas Cowboys defensive tackles coach.

The suspension, which caused him to miss 16 games, including the first 13 of the 1997 season, proved to Lett that he had the mental toughness to survive the worst of mistakes and showed him that he didn't have to keep being his own worst enemy.

It forced him confront his insecurities and learn to embrace success. There was no need, he discovered, to fear success and sabotage himself, because he was worthy of the attention and adulation that his prowess on the football field had attracted.

That's why Lett, who earned a spot in the Pro Bowl in 1998, views second-year defensive end Randy Gregory differently than others in the organization do.

Cowboys defensive end Randy Gregory will miss the first four games of the 2016 season after violating the NFL's substance-abuse policy. AP Photo/James D Smith

"I trust him," Lett said. "I've been where he's been. I know what it takes to overcome it."

Lett talks to Gregory often about the mindset it takes to win on the field and the preparation it takes off the field to position himself to succeed.

One season into his NFL career, Gregory has already put his future in jeopardy.

The 23-year-old defensive end been suspended for the first four games of the 2016 season for violating the league's substance-abuse policy. Finding himself in this predicament means that Gregory has violated that policy at least three times since testing positive for marijuana at the NFL scouting combine last year.

It’s fair to ask whether the Cowboys should have passed on him in the second round because of the issue, but they thought Gregory's immense talent was worth the risk.

He has every skill -- speed, strength, power and the ability to bend -- needed to be a dominant pass-rusher, but he doesn’t play with the confidence of a man with that skill set.

"Sometimes, guys are so talented they don't know how they make certain plays, they just do it," Lett said. "So they don't always have the most confidence. I've been where Randy is. He can't take all that stuff on the field with him, he just needs to play. He might need to reach inside himself and pull out his inner Charles Haley and just get angry and take it out on the other team."

For now, Gregory's potential makes him worth the risk. At some point, though, he must perform.

"It's a work in progress,” Cowboys coach Jason Garrett said. “He’s gotten better, but he has a long way to go. A lot of guys have a long way to go.”

A lot of guys, though, weren’t drafted to be dominant pass-rushers. Gregory did not have a sack in his rookie season, but he recorded 16 quarterback pressures and 11 tackles.

Gregory has yet to discuss his suspension. During the club’s annual golf outing a few weeks ago, he wasn’t made available to talk, and during organized team activities each of the past two weeks, he has not been in the locker room.

He hasn’t tweeted since Feb. 17, the day before the NFL announced his four-game suspension.

The failed test before the draft is why Gregory, a top-10 talent, dropped into the second round.

For now, most team executives can't trust Gregory. Why should they? He hasn’t earned it.

All they can do is hope he can find the willpower to defeat his addiction. And it's definitely an addiction; just look at what he's jeopardized to smoke marijuana.

"That's a hard question," Cowboys vice president Stephen Jones said when asked if he trusted Gregory.

"At the end of the day, when you have someone who has this type of illness, you have to get the right infrastructure in place and the right support system to give them the chance to succeed. And that's what we're doing with Randy.

"And he's a good person, and when you visit with him, I think he's somebody who is the first to tell you twice that he's got challenges to overcome. I think the best way to say that is he's a good person. He's wanting to do things the right way. And we'll continue to support him until obviously he does something that we have to hang it up.”

Garrett has expressed his disappointment to Gregory, but he hasn't focused on Gregory's transgressions.

“Certainly it’s very disappointing, and we’ve made that abundantly clear with him, and he understands that more than anybody,” Garrett said. “But at some point, you have to say, 'OK, this is what happened, this is what the consequences are for that action, and now we're going to get to work. I've got to make sure it doesn't happen again, and I've got to get to work as a football player to become a better player with the opportunities I do have.' That's what our emphasis is with him and really with the rest of the guys."

There's no guarantee that this approach will work. All the Cowboys can do is hope Gregory continues to listen to Lett and becomes the pass-rusher they envisioned when they drafted him.