“Henry is growing up. Henry understands the responsibility that he has,” Georgetown Coach John Thompson III said of center Henry Sims, above. (John McDonnell/The Washington Post)

Georgetown’s Henry Sims had one goal in mind during the offseason: sweat the details in preparation for his senior season, his first opportunity to entrench himself as starter for the Hoyas.

He rededicated himself in the gym, where the 6-foot-10, 245-pound center spent the majority of his summer sharpening his agility, dribbling, passing and shooting free throws. When he wasn’t on the hardwood, he was watching video of himself and his opponents.

You name it, Sims said confidently last week at McDonough Gymnasium, and he worked on it.

“I put in the work in the offseason,” Sims said. “I was a lot more basketball-focused than I had been in the past. And now, I’m reaping the benefits of that. I feel like this season is going to be a chance for me to show off what I’ve been working on.”

The early returns on Sims’s effort are encouraging. In the Hoyas’ season-opening romp over Savannah State on Nov. 12, he dominated the paint, scoring a career-high 19 points on 9-of-11 shooting. He also grabbed six rebounds and was credited with five assists.

Two days later in Georgetown’s 86-45 thumping of UNC Greensboro, Sims finished with eight points, seven rebounds and three assists in 17 minutes as Coach John Thompson III used the second half to play his touted freshmen.

As a reserve last season, Sims averaged 3.6 points and 3.2 rebounds in limited playing time. He scored in double digits twice and hardly played in the postseason.

“I knew Henry had this in him,” fellow senior Jason Clark said. “He can do a lot of things with the ball. He can score. He can rebound. He can block shots. He just needed confidence. I saw him in the gym this whole summer working hard. I knew it was coming for him. This is going to be his year to break out.”

As solidly as Sims has started, the Baltimore native is fully aware that the Hoyas’ first true test is Monday night in Hawaii, where he and his teammates open the Maui Invitational against No. 12 Kansas.

Sims said he’s excited to face 6-10, 237-pound junior forward Thomas Robinson, a Washington native who played at Riverdale Baptist as a high school junior before spending his senior season at Brewster Academy in New Hampshire. Robinson had 11 points and 12 rebounds in the Jayhawks’ most recent outing, a 75-65 loss to No. 2 Kentucky.

If the Hoyas upset the Jayhawks, they’ll face the winner of the game between host school Chaminade and UCLA in Tuesday’s second round. The prestigious tournament also features No. 6 Duke, No. 10 Memphis, No. 17 Michigan and Tennessee.

“It’s going to be a big test,” Sims said. “I honestly can’t wait.”

Thompson III said the key for Sims this season will be focusing on putting forth a consistent effort from possession to possession and game to game, not worrying about his stat line. In the waning minutes against Savannah State, the Verizon Center crowd recognized Sims’s dogged pursuit offensive rebounds and hustle at both ends with a standing ovation as he took a seat on the bench.

“Henry has to make the hustle plays,” Thompson III said. “When Henry gets himself in trouble [is when] he starts to thinking about being a playmaker, when he starts to think about scoring. But he does pretty well when it’s just effort, effort, effort. He has to make the effort plays and everything else will fall into line.”

In addition to honing his skills, Sims said he’s added about five pounds of muscle to his already solid frame and has also benefited from the tutelage of Hoyas great Othella Harrington, who was hired in May as the assistant director of basketball operations. Harrington is Georgetown’s all-time leader in offensive rebounds and ranks fifth in points and blocked shots. He also played in the NBA for 12 seasons.

“He’s been a big help to me,” Sims said of Harrington. “He’s been where everybody is trying to go. It’s really helpful having someone like that in your ear. He has all his tricks of the trade and he’s teaching them to me. I’ve never had that.”

While Thompson III acknowledged Harrington’s influence, he pointed out that Sims’s success — or lack thereof — in his final season on the Hilltop will be determined by Sims, and no one else.

“A lot of Henry’s development goes back to Henry,” Thompson III said. “Henry is growing up. Henry understands the responsibility that he has.

“You come in as a freshman, sophomore, you’re just kind of wandering around,” the coach added. “Then, all of a sudden, senior year gets here and you’re like: ‘I’m not coming back next year. I need to start to get a little more serious and take steps to prepare myself for the next phase in life.’ ”