Oftentimes an overlooked aspect of an NBA rebuild is the supporting cast. Franchise players are critical, and creating a championship contender means finding Hall of Fame talent. Supporting cast starters come from those late Lottery to mid-first round selections, and free agency is critical to plug holes once those young players are ready to contend.

But what about the bench? What about the situational role players that can turn a game on its head at a moment’s notice? What about that tired-but-true cliché of players doing the little things?

It’s critical. It’s necessary. The Tony Allens, the Shane Battiers and the Shaun Livingstons make good teams great, and great teams elite. And what the Bulls have in small forward Shaq Harrison is the early stages of a glue guy, a role player and a defensive star who they’d be wise to hang on to.

Wednesday’s effort against the Wizards was vintage Harrison with an added bonus. Starting for the second time in as many games, Harrison finished with 18 points on 7 of 13 shooting and four steals and provided more elite defense, this time on All-Star Bradley Beal. This came two nights after a four-steal performance against Devin Booker and the Suns, the team that cut him in training camp last September.

“Defensively he’s like a mad dog chasing a meat truck,” Jim Boylen said before Wednesday’s overtime win. “But he’s playing in a system now and it’s great to see what he’s doing.”

To say that Harrison has been good on the defensive end would sell him incredibly short. His on/off numbers won’t impress because he’s usually on a second unit that features players like Cris Felicio, Antonio Blakeney and Wayne Selden that hurt his numbers.

But in a league that’s increasingly focused on offensive numbers like never before – and it becoming difficult to find relevant defensive numbers – Harrison is absolutely thriving on the other end. Though he’s averaging just 18 minutes per game, Harrison is second in the NBA in deflections per 36 minutes (3.9), first in steals per 36 minutes (2.4) and his average defensive speed of 4.50 miles per hour is the fastest in the NBA.

Harrison isn’t just a really good defensive player; he’s a great one.

“Defense is 90 percent effort, 10 percent talent,” he said after Wednesday’s game. “I guess that 10 percent shows sometimes, but it’s 90 percent effort. Anybody can go out there and play hard any day and make things happen.”

Harrison is selling himself short. He was the primary cover on Beal in the second half and overtime, when Beal went 4 of 13 for 12 points. This is the same Beal who entered Wednesday’s game averaging 30.0 points on 50 percent shooting since Feb. 9. Harrison hounded him most of the second half and made life miserable for the potential All-Pro shooting guard.

“Grit, grind, fearlessness. He’s a very smart player, especially on the defensive side,” Kris Dunn said. “He’s in the right spots but at the same time you can put him on somebody and he’s going to go out there and work hard and try to make everything difficult for that person.

“He plays hard, great feet, great hands, athletic. He a dog. When you’re a dog on the defensive end that gives you a little extra.”

Perhaps Harrison’s defensive effort has given him more confidence on the offensive end. After all, two of his steals on both Monday and Wednesday led to his own fast break buckets. That’s a free 8 points on 4 of 4 shooting. But Harrison has done even more than that.

Wednesday was his best effort of the year as a scorer, filling that third option void for the Bulls who were without Zach LaVine and Otto Porter Jr. Harrison’s 18 points were the most he’s scored since a 20-point effort in December, though that came in the infamous 56-point loss to the Celtics.

This time around Harrison did his damage in a win and it was a continued trend of efficient basketball. Prior to Jan. 29, Harrison was shooting a team-worst 50.4 percent in the restricted area and 22 percent in the paint. Since then, he’s 60 percent in the restricted area and 45.5 percent in the paint.

He’s never going to be a shooter – though he made his second triple in his last 19 games on Wednesday – so Harrison is focusing on what he does well. He’s living in the paint and moving the basketball when he can’t get to the basket.

“I’m watching film, I’m getting in before practice, I’m getting shots up and going over schemes with the coaches and trying to play at a controlled pace,” Harrison said of his improved offensive play. “And I think it’s paying off. I’m going to continue to keep working at it and get better.”

Anything Harrison provides on that end of the floor is a bonus. He’s going to make his money and stay in the NBA because of his defense. But what the Bulls have unearthed in Harrison is a keeper. The Bulls are 25th in defense this season and while Wendell Carter Jr. will improve them next season, this is still a team built around offensive talent in Zach LaVine, Lauri Markkanen and Otto Porter Jr.

Harrison gives the Bulls something they desperately need: a talented defender on the wing. He’d give the Bulls a re-do on swapping David Nwaba for Jabari Parker this past offseason, he’d solidify the Bulls’ second unit with a defensive stopper and someone who could be an offense-for-defense substitution late in games.

He has a team option for next season that the Bulls will undoubtedly pick up, but they could go a step further by extending him to a longer-term deal. He’s already 25 years old, so this isn’t as if the Bulls have found a young hidden gem. But Harrison hasn’t stopped improving since he debuted in October. The defense has only gotten better, the offense has slowed down for him and he fills a need. His ceiling is capped by his offensive limitations, but there still feels like there’s a lot of potential there.

The Bulls have their frontline talent in Markkanen and LaVine, they have an excellent supporting cast with Porter, Carter and potentially Chandler Hutchison. They’ll also add a top-8 pick in June. Harrison couldn’t complement that cast of players any better. He could be the Allen, the Battier, the Livingston as the Bulls look to build a playoff contender.

“I think as much as this league is about playoffs and great players and great personalities and all those things, this league is about improvement (and) development,” Boylen said. “And seeing an undrafted guy come in and get better and grow, he’s improved his finishing, his ball handling, his decision making, his shooting.

“When you see guys improve and grow, I don’t think there’s anything better.”