The Wizards feel Chris Singleton, left, and Shelvin Mack bring both character and toughness to the remade roster. (Bill O'Leary/Washington Post)

Before Ted Leonsis took over as owner last June, the Washington Wizards were known as a team that liked to score points, crack jokes and do little else. But the Wizards are attempting to do something that’s either backward or revolutionary: To get more mature while getting younger.

Tuesday, the team introduced draft picks Chris Singleton and Shelvin Mack — two more players who spent three years in college and are barely old enough to legally drink — and it expects that both will bring a more serious attitude, a defensive mind-set and continue the franchise’s personality makeover that began when it selected John Wall No. 1 overall last June.

“They fit into what we are looking for. We’re looking for people to have character,” Coach Flip Saunders said of Singleton and Mack at a news conference at Verizon Center. Wizards President Ernie Grunfeld “and I and Ted, we’ve talked plenty of times. There are a lot of teams that have talent to win games, but you have to have character to win championships.”

In the past year, the Wizards have drafted seven players and traded for another first-round draft pick. Now, six players on their roster next season will be age 22 or younger. Wall, the presumed leader, remains the youngest on the team at 20.

The common thread for those additions is that each player is considered to be a tough, fierce competitor. Singleton and Mack also arrive in Washington with something to prove. They are familiar with each other after both were on the select team that scrimmaged with Team USA before it won the world championship in Turkey last summer.

Singleton, the Florida State forward considered the best perimeter defender in the draft, is upset that 14 teams passed on him and allowed him to fall to 18th in last Thursday’s draft. Mack, a combo guard expected to back up Wall, considers himself forever an underdog as he overcame the slights of being an unheralded “two-star recruit,” went on to lead Butler to consecutive NCAA championship games and still fell to the Wizards in the second round at No. 34.

“Our plan was to get more athletic, to get tougher, to get better as a defensive team,” Grunfeld said. “We think both have very good futures ahead of them.”

The Wizards had Singleton rated as a top-10 talent and were stunned that he was available with their second pick of the first round. Singleton said he expects to bring a defensive presence to the team “right off the bat” after guarding stars such as Derrick Rose to Kevin Durant at those Team USA scrimmages.

“I don’t shy away from challenges. It’s something I look forward to. I get to play with the best superstars in the world,” Singleton said. “Basically this is an opportunity for me. We’re a young talented team. Everybody knows we can score the ball. On the defensive side, we’re just going to push ourselves.”

Mack confirmed Singleton did a solid job defensively against those all-star players. He added that he would like to continue the success he’s had at Verizon Center, where Butler won two games in the NCAA tournament in March and advanced to the Sweet 16 despite Mack committing a “dumb foul,” when he inexplicably clobbered Pittsburgh’s Gilbert Brown near midcourt with 1.4 seconds left. The play earned Mack an invitation to ESPN’s ESPY awards, but Saunders had to ask, “Not going to happen again, right?”

“Nah,” Mack replied.

“I’m going to bring the team toughness,” Mack said. “I know I’m not starting; John Wall is the starting point guard. I’m going to try to make him better in practice. I know he’s going to try to make me better and just enjoy the challenge of being in the NBA.”

Saunders said he expects veterans Andray Blatche, Nick Young and JaVale McGee — the last remaining players on the roster who pre-date Leonsis — to adjust to the changing environment. Blatche and McGee are under contract next season and the team hopes to bring back Young in free agency after making him a qualifying offer earlier this month.

“I think they are ready because they are not young players . . . now, before you know it, you’re going to be done playing. They have to take it to the next levels,” Saunders said. “The players you bring in, they are serious players. The more players you bring that are like that, then the other players become the abnorm. All those guys, they want to win. Many times we talked in the past, they’ve talked about what they want to do individually and talking to them now, the first thing they bring up is what they want to do as a team and getting to the playoffs.”

“You look at the teams that flourished in the playoffs, and they were big, they were tough, they played defense. And so we’re trying to remake the team,” Leonsis said during a news conference introducing Jan Vesely, the team’s top draft pick at sixth overall, on Monday. “You can’t teach some of those things. And adding that kind of bulk and strength, along with great talent, is what we promised John Wall, that we would be rebuilding the team and coach would be implementing a system that took advantage of the strengths and character of the players that we were bringing in.”