"I feel like the play is faster in the NHL, so to come back and bring that fast play to this level, doing everything faster, that's the difference between the NHL and the AHL is quicker play," Johnsson said. "So it helped me to be (in the NHL) to play faster now that I've come back."
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Johnsson, 23, leads Toronto with 15 points (six goals, nine assists) in nine playoff games and is three points behind Chris DiDomenico of Rockford for the AHL lead.
Coach Sheldon Keefe said Johnsson, who was selected by the Maple Leafs in the 7th round (No. 202) in the 2013 NHL Draft, has always been a capable player defensively, but has evolved his game offensively since coming to North America full time at the start of the 2016-17 season.
"He's always been an offensive player, but he's taken it to another level where he's now a dominant offensive player," Keefe said. "He's gone from a guy who's been very reliable, but now just with the confidence he has, it's just clicked for him offensively where every shift he feels like he can make a difference."
Johnsson, who had 54 points (26 goals, 28 assists) in 54 AHL regular season games after having 47 points (20 goals, 27 assists) in 75 games last season, was quick to identify the reason why his play has improved.
"It's my transition game," he said. "I feel like I had it a lot when I was younger, and I feel like that's come back now in North America. I feel like I've developed that the most, and now it allows me to create more on the rush and hold the puck in the offensive zone."
Johnsson has found success playing primarily on a line with center Miro Aaltonen and left wing Carl Grundstrom.
"We help each other a lot. We play quick and fast and help each other get out of tough situations," Johnsson said. "We can trust each other that someone is going to protect the puck in the corner and then put it in a good spot. That's what we've done best is to move the puck quick."
However, after spending time in the NHL this season, Johnsson (5-foot-10, 180 pounds) said improving his strength will be a main focus over the summer.
"I just want to get stronger overall in my body, to get heavier," he said. "I mean, I'm a bit shorter and I'm not going to go body on body on anyone who is taller than me, that's not my game. But just trying to get pucks out at the line, I just want to get stronger so I can have the stamina to do it more often.
"[The Maple Leafs are] obviously not going to be the same team as this year, so it's hard to say right now, but of course, my goal is to get a higher spot (in the lineup)."