He was the forward's coach with Mora IK in the Allsvenskan Swedish league during the 2015-16 and 2016-17 seasons. It's no surprise that when scouting the pupil, the Blackhawks brass sought out the teacher's grade.
"They do their homework, so it would be natural for them to ask my opinion and I gave it. Obviously, I like him a lot," Colliton chuckled. "He's a good player and I'm proud of him."
With Allsvenskan, and under Colliton's tutelage, Nilsson took a massive step forward in offensive production in 2016-17. Nilsson improved his goal total by 11 from the previous year to finish with 42 points (20G, 22 A) in 46 games.
Colliton says when the coaching staff first had Nilsson they didn't realize how skilled he was.
"I just liked how competitive he was, that he was responsible defensively and worked hard. We saw he could make plays and contribute offensively. When he first came, we had a lot of new faces and as a first-year guy he had to kind of pay his dues. He didn't get any power-play time until the second half. Once he went on the power play, he really took off and he had an outstanding second half that year, but he didn't really produce."
The stat sheet did not reflect Nilsson's play, but the second half of 2015-16 gave the young forward confidence heading into the next season. He immediately became a difference maker for Colliton's staff to deploy in a number of ways.
"He played a big role for us offensively, and then because he could help us score more goals I used him in a different way than I had the year before," said Colliton. "I played him in more offensive situations and maybe saved him defensively when the year before it was maybe the opposite."
Colliton says the Blackhawks are getting a skilled forward who is a good skater, but it's his competitiveness that stands out the most.
"He loves to play, loves to win," said the coach. "He wants to be great and he's coachable. He sees the ice really well and thinks the game really well, so he'll be a nice addition."
Appreciated for his ability to see and think the game at a high level, Nilsson is a valuable complementary piece for other skilled players.
Nilsson stepped up to the top league in Sweden this past season, scoring eight goals and adding 10 assists in 40 games.
The 24 year-old's first season in North America is likely to be spent in Rockford, back with his former coach, as he gets used to a new level of competition and the differences in the game. But if anyone has faith in Nilsson and his future, it's Colliton.
"I think it's unfair to expect him to step right in. It'll be his first time on the small ice and his first year in the top league was last year. Certainly, I think he has a chance to play in the NHL - no doubt. But you've got to be patient."