TORONTO -- As Philadelphia limped to another losing campaign during the 2014-15 season, 25 players appeared in at least one game with the rebuilding Sixers. Tony Wroten was the team's leader scorer. Nerlens Noel appeared in 75 games and nearly averaged a double-double. Michael Carter-Williams, Henry Sims and JaKarr Sampson all started at least 30 games. Scroll down the list, and Philadelphia's roster included cameos from Alexey Shved, Isaiah Canaan, Thomas Robinson and JaVale McGee.

Only one of those 25 players is still on the Sixers roster today.

In November 2014, Philadelphia signed Robert Covington to a four-year, non-guaranteed contract. Covington went undrafted after four seasons at Tennessee State and appeared in seven games with the Rockets during the 2013-14 season, when he was named the 2014 D-League Rookie of the Year with the Rio Grande Valley Vipers. Few expected the 6-foot-9 forward to be anything but a shot-in-the-dark signing. At the time, some even believed giving Covington significant minutes would help enhance the Sixers' chances of losing more games and improving their lottery odds.

Brett Brown and his coaching staff had other plans.

They saw the potential in Covington to go from a spot-up 3-point shooter to a player who was capable of impacting the game on both ends of the floor. Around the league, teams pay a premium for players who can shoot and defend at a high level. The Cavaliers agreed to trade Kyrie Irving to Boston partly because they were getting pieces back that included Jae Crowder, a premier three-and-D player with the Celtics. Boston has targeted players with elite shooting and defensive potential in the draft, selecting Jaylen Brown and Jayson Tatum in back-to-back years. The Raptors paid $60 million for DeMarre Carroll to be the complementary piece to Kyle Lowry and DeMar DeRozan. The signing didn't pay off, but Toronto might have found its future three-and-D stalwart in rookie OG Anunoby.

The Sixers have found their three-and-D specialist in Covington.

After averaging 13.5 points and 1.4 steals in his first season with Philadelphia, Covington had steadily improved and is now the team's best defender on the perimeter, guarding multiple positions and disrupting opposing offenses with his read-and-react skills. Last season, Covington led all small forwards in defensive real plus-minus. He finished fourth in Defensive Player of the Year voting. Last month, the Sixers rewarded him with a four-year, $62 million contract extension.

Brown and assistant Lloyd Pierce keep effort charts that track each players' defensive impact on the floor that goes beyond the box score. Covington routinely grades out as an "A." It doesn't surprise his teammates.

"He's a special player," teammate Trevor Booker said. "He can shoot the ball, he can drive it, he defends, he plays hard. That's the kind of player we need. He's not afraid to get down and dirty. That's the type of player the coaching staff likes, and the fans in Philadelphia definitely love players like that."

Through 31 games this season, Covington is averaging a career-high 14.6 points, along with 6.1 rebounds and 1.9 steals. He is also shooting 39.3 percent from three.

T.J McConnell is in his third season with the Sixers, and has endured the losing in Philadelphia alongside Covington. He's also seen his teammate's development up close. "Guys like him are few and far in between," McConnell said.

A Christmas Day win over the Knicks at Madison Square Garden stopped a five-game losing streak for the Sixers. At 15-18, they're still on the outside looking in for a playoff spot, but Brown and the players in the locker room know that if they can stay healthy, the postseason remains a realistic goal. Joel Embiid and Ben Simmons make the team go, but teammates know Covington is just as crucial to the Sixers' goal of earning their first playoff spot since the 2011-12 season.

"Everyone talks about him as one of the best three-and-D guys in the league, but he's not just a 3-point shooter and a great defensive player," Dario Saric said. "There's so many more things that he does. He's got one of the biggest roles here. He's so important to this team."

J.J. Redick has a more succinct assessment of what Covington brings to the Sixers. "He's the perfect modern day player in terms of analytics and what he's able to do on both ends of the floor," Redick said.

The stats back up Redick's claim.

Covington is sixth in the league in real plus-minus this season, behind only James Harden, LeBron James, Stephen Curry, Giannis Antetokounmpo and Russell Westbrook. With the exception of Curry, who has missed significant time to injury, those are five MVP candidates ahead of Covington. Per Covington is second in the league with 3.9 deflections per game, which trails only Paul George. His 1.94 steals per game are tied for fourth in the league. He's fifth in 3-pointers made and has one of the league's best effective field goal percentages on catch-and-shoot threes.

And per, the Sixers are +4.7 and allowing 100.8 points per 100 possessions with Covington on the floor. Without him, they allow 108.5 points per 100 possessions and have a -9.9 net rating. The lineup of Embiid, Simmons, Saric, Covington and Redick is outscoring opponents by 15.1 points per 100 possessions, which is the fifth-best net rating for any five-man unit in the league that has logged more than 200 minutes together this season.

"Ben penetrates and draws a lot of attention," Covington said. "Same with Joel. He commands so much attention in the post so whenever they try to double-team him, he can kick it out to me, or he can find more space because of how teams are guarding me because I'm a deadly 3-point shooter."

When Embiid, Simmons and Covington are on the floor together, the Sixers are outscoring their opponents by 12.8 points per 100 possessions.

The rebuilding process in Philadelphia has often been talked about with broad strokes. Former general manager Sam Hinkie's plan has often been summarized as losing a lot of games to acquire superstar talent through the draft. While that is true, Covington's development into one of the league's elite two-way players ranks high on the list of accomplishments during Hinkie's tenure with the team. The former general manager even devoted an entire paragraph in his infamous resignation letter to Covington, admitting it was a mistake to not acquire him after he went undrafted in 2013.

"He's homegrown," Brown said. "He's a by-product of our version of development and the years that we have spent at the bottom. He's a by-product of the opportunity that somebody gets and he's taken advantage of it."

In five years, Covington has gone from undrafted to one of the most important players on a team with designs on contending in the Eastern Conference for years to come. But his process, in many ways, is just getting started.

"It's a testament of hard work," Covington said. "I'm the only player that's been through all that's been going on here the last four years. Even though I've gotten to this point, that doesn't mean the work stops. I've been someone who has always played with a chip on my shoulder. Just because I'm in a different place now, it doesn't mean I'm going to sit here and lose my focus on what got me here."