Now his numbers in the EYBL aren't necessarily popping, as he's struggled shooting the ball from the field. But the advancements he's made to his game and conditioning are evident.
"I'm just working on my physical conditioning, strength and quickness," Ellenson, who plays with Duane Wilson's Playground Elite team, told Scout.com.
"I've been getting after it during the off season any time I can I've been getting in the gym and the weight room," he added.
Ellenson has improved as a prospect. He's more mobile, fluid and athletic than this time last year. He creates mismatch problems with versatility, as he has the hands, touch and post scoring ability to be a threat on the block, but can also face the rim and make jump shots.
"I'm a guy that can step out and hit a shot in your face or take you into the post or blow by you off the dribble," Ellenson said.
"I've just been working on my speed and quickness and I'm just showcasing it because I haven't really been able to show people that I have handles," he said.
Ellenson is averaging 15.2 points and 8.9 rebounds a game through eight EYBL games.
On the recruiting front, Ellenson said he's been "pretty busy."
All three of those schools have offered Ellenson a scholarship. To date, he's taken unofficial visits to Northwestern and Wisconsin.
"It was good," he said of his Northwestern visit. "I got to talk to a couple of guys. I met their president. I got to meet the coaches and meet Mike Wilbon down there. It was the whole deal. It was pretty neat."
"Wisconsin they had a big win against Michigan State," he said about his visit to East Lansing. "Traevon Jackson hit a game winner. It was nice to see the crowd and arena."
Does Ellenson, a standout at Rice Lake (Wisc.) High, have intentions of playing close to home?
"It'd be king of cool to be that in-state guy, but we'll just see how it all works out because you do get pressure form the in-state school for sure," he said.
To go with the schools he's visited and has offers from, Ellenson said Duke, North Carolina and most recently Kentucky are involved in his recruitment. Creighton, Michigan and others are also recruiting him.
"I'm going to try and call schools and let them know," Ellenson said when asked if he was starting to dive into the process more. "I haven't come out with a list, but this fall is when I'm going to take my visits."
Ellenson, who is due a bump in Scout.com's rankings when they are updated, is currently regarded as a four-star recruit in the 2015 class.