Perhaps the happiest player on the football field during the Chiefs’ rookie camp this weekend was also the tallest — and one of the most athletic.

At 6 feet 7 and 272 pounds, defensive lineman David Irving looks the part. Throw in an impressive 4.84-second 40-yard dash time and 38-inch vertical and 128-inch broad jumps, and it’s easy to see why the Chiefs were one of seven teams to trek to San Jacinto, Calif., to watch Irving’s personal pro day in March.

Irving, who signed with the Chiefs as a priority free agent, showed flashes of that talent this weekend.

His size-speed combo stands out, at least until he starts getting tired: He was dismissed from the Iowa State football team in April 2014 and last played in a game nearly 18 months ago.

“I got to get back in cardio shape — I know you guys saw that,” Irving said with a laugh, referring to his first practice on Saturday. “Going from special teams, then individual, then straight over to team (drills), I was pretty tired. But it feels good to be back out there.”

In many ways, however, Irving feels grateful to have the opportunity at all.

“It was a blessing, honestly,” Irving said of his chance with the Chiefs. “After leaving Iowa State, I wasn’t sure what I was going to do, if I even had a shot at the NFL.”

In April 2014, Irving attended VEISHA, an annual student-run festival in Ames that is known for excessive partying, when a riot broke out and Irving was photographed and videotaped holding a stop sign, which he argued was handed to him by another person. The picture went viral on social media, nevertheless, and Irving was charged with fifth-degree theft, disorderly conduct and criminal mischief.

Irving was dismissed from the team. Six months earlier, he was suspended for a game after he was charged with domestic abuse against the mother of his child. The charge was later dropped.

Chiefs coach Andy Reid said general manager John Dorsey and the scouting department made sure Irving “would fit in here and that he kind of had things going in the right direction.”

“We knew he was a good football player,” Reid said. “He had some issues, obviously.”

Irving is one of two Chiefs priority free-agent signings who has faced a domestic-violence charge. The other is cornerback Justin Cox, who was arrested in November but later pleaded guilty to a misdemeanor charge of trespassing when the alleged victim asked for the domestic-violence charge be dropped.

Reid said the Chiefs did background work on Cox — who was suspended by Mississippi State for the final three games of the season — just as they did with Irving.

“He, too, had some issues, and it’s important that they stay on top of that,” Reid said. “They did well footballwise (this weekend), which we figured they would — they’re good football players. But there’s another part of that, and football’s not going to be there the rest of their life. You’re going to have to be able to handle things outside the football world, and handle those things the proper way.

“We’ve done a lot of homework on them, and we felt comfortable they were heading in the right direction.”

Both players said they made mistakes.

“It’s not who I am,” said Cox, who said he also drew interest before the draft from the Seahawks and Patriots. “I made a mistake and I’m just building from it. Can’t go back to the past. I’m coming here to do what I got to do — play ball and learn from the veterans and do what I got to do to make the 53.”

Likewise, Irving said every team he spoke to before the draft asked him about his past.

“I made the mistakes I made — I just want to convey that is part of my past, I moved on from there,” Irving said.

“I’m a better man, learning from my experiences, and here I am now.”

Irving said the dismissal gave him a chance to take stock of his life. He worked to stay in shape back home in San Jacinto, hoping an NFL team would still take a chance on him. When football season started — and the Cyclones finished 2-10 without him — he came to realize how much the game mattered to him.

“I watched all the Iowa State games,” Irving said. “I wished I was out there. It humbled me. It made me work harder. It made me hungrier, more motivated and luckily I got a chance to be here. And I’m here and I’m very appreciative, just ready to get back to work.”

The Chiefs seem willing to believe Irving and Cox. Reid said that when bringing in players with off-field issues, a team has to first believe that they want to do better.

“No. 1, you’ve got to have a (feeling) that they want to change,” Reid said. “Whatever degree it is, people maenke mistakes. And then, it’s important that you admit your problem, and that you go fix it. We felt that they, again, were headed in that direction. So we’ll see. Time tells on those things.”

Indeed. But Irving knows the stakes.

“It means everything — this is my future,” he said. “Obviously, I can make something for my family. I have a daughter. They gave me an opportunity that no one else would give me and like I keep saying, I’m highly appreciative, man.”