"I started off playing tennis when I was younger and I didn't start playing ball until I was 15," he said. "I didn't even make varsity on my freshmen team. I sat the bench for two years, and I started playing this year.
"People just haven't noticed me because I'm up in Boston and there's not a lot of [high school basketball] media there."
But at the Nike Camp last week, coaches and scouts took notice.
"When the coaches came, I stepped it up – picked up my intensity," he said. "The first couple days I had to get used to playing kids my size, but I think I did real good, matched up with the best there. I just wanted to put my name out there and see how I stack up and where I could be ranked."
And there is no doubt he will be ranked among the nation's top big men, and his stock has only just begun to rise.
In BABC's opening game at the Peach Jam on Sunday morning, Sims posted 20 points (7-9 FG, 4-6 FT), five boards and five blocks, by our unofficial count. And note that he sat out most of the second half, as BABC routed the D.C. Blue Devils.
Sims' points came in the paint, on low post moves and dunks – and then there were the two three-point attempts, both of which he swished.
So he's a three-point shooter, too?
"Yeah, when they first put me on the team, all I could do was shoot," Sims said. "I couldn't play down low, rebound or anything like that. Just shotblock, shoot and pass. I just started getting good down low."
His post skills are only part of the versatile game Sims is trying to develop.
"I don't want to be a big man who's just big," he said. "I hate it when people think I'm good because I'm tall. If someone's bigger or stronger than me, I want to be able to take them outside and go past them."
With his size and mobility, many of the nation's elite schools are getting involved.
"Memphis, Stanford, Michigan (who offered this past week), Tennessee, Kansas are some of the ones that only just came in," he said, mentioning that New England schools such as Boston College have been recruiting him for a while.
North Carolina assistant Fred Quartlebaum sat courtside for the Sunday morning contest, getting his first look at Sims. Sims said the Tar Heels made a first phone call to his coach a few days ago.
"I want to get recruited by North Carolina," he said.
As for the major factors in his decision?
He said he doesn't need to start as a freshmen, but is looking to get significant playing time early. And, while distance from home is of note right now, the AAU circuit is helping him learn to be away from home and may not remain a major factor.
With new schools showing interest each day, Sims is "wide open," though he plans to figure out in August his fall official visit schedule.